Why are there transgender veterans who support banning currently serving transgender service members but won't discuss it?

It doesn't work well. And trying to be something you were not born and depending on medical support when deployed is an issue.

I am not transgender, so I would not presume to explain why a transgender service member would support banning transgender people from joining the service.

That said, I will offer offer my opinion, freely admitting that I do not know how much I do not know.

It is a common mistake to believe that the next war will be the same as the last war. In a symmetrical warfare scenario, the logistical effort may be much more complex. Difficult delivery of person specific meds may overly burden the supply train. And has been a standing reason for banning a number of people with a variety of medical conditions from service. Although not, medical supplies, it was my experience in the Marine Corps that during peace time, personal mail could chase you around the Pacific or Mediterranean for weeks, frequently arriving out of sequence.

It is my poorly informed understanding that transgender people suffer a substantially higher level of mental health problems, particularly suicidal ideation. That may be a contributing factor, particularly in the crucible of deployment, and furthermore combat theater deployment.

I do believe the "gross, icky, and confused" concern exists. That does not mean I think it is valid. At various times different subsets of American Society have been too "gross, icky, and ______." As examples and by no means all inclusive list: Irish, Blacks, Italians, Asians, Catholics, Jews, Muslims, Sikhs, Mexicans, Puerto Ricans, etc. etc. etc. It seems that eventually, given enough time and no choice, the military adapts; typically faster than the civilian populace.

So, I have known and do know a fair number of trans servicemembers. I've been in units with them and have never, ever had any issues with trans servicemembers. All of my Soldiers have been Soldiers first and everything else second. I fully support trans servicemembers serving in all branches and services and I think the "ban" is a knee-jerk religious conservative overstep by people who don't understand and are not comfortable with other people feeling different than they look.

All of that being said, this is my understanding of the primary reasons for the transgender service "ban."

1. The resource costs associated with the actual transition process are not in line with standard, expected, medical costs associated with able-bodied enlistees. We don't let others in with a lot of other known medical issues that require extensive resources to treat.

2. Some people view transgender as a type of mental illness because a person doesn't feel like the gender they happen to have physical parts for.

I think those are the two I hear most often.

With regard to any argument that the other Soldiers aren't ready, so it interferes--I call bs. That argument fails to consider that it is the same one used for other integrations--race, gender. Those are working.
Admittedly, I've not educated myself on this multifaceted issue. My basic understanding is, a person born with the physical organs/parts of one gender, identifies psychologically, as the opposite gender.
First, it may be for me to research, but in my day, that would be gay, lesbian, or bisexual. I understand it isn't solely about sex, and I'm aware of historical examples of people who disguised themselves and lived as a member of the opposite gender. Since they're dead, we can't ask whether they did it for identity, or to pursue an occupation that would have prohibited their actual gender from participating.
I do believe, in part, this issue is being politicized because it appeals to 2 separate bases.
With regard to any surgeries or other medical treatment, I oppose those on the basis of cost, lost work time, liability for compensation claims, and deployability.
With regard to any negative effect on good order and discipline, I'm not certain I accept it as valid. Those who opposed racial and gender integration made similar arguments that have been proven wrong. My experience is Soldiers are going to give their peers a hard time, and a harder time for those who don't perform, or who can't take a joke. There will certainly be those who oppose it based on bias, religious beliefs, or any another ideals, just as was used for other integrations. Soldiers worked through those, and the professionals based their treatment on peers on performance.
Essentially, I believe Soldiers can learn to accept someone's identity, and despite any opposition to it, can work with the individual. The problem, IMO, is if there is any real or perceived advantage for another Soldier.
Examples of real or perceived advantage:
Surgery, convalescent leave, profile recovery time, nondeployable time.
Male identifies as female, graded on APFT using female standards. (Note: I don't know what is used, as I've done no research. Reason for raising this is there was a male competitive power lifter who never won. After some time, he identified as a woman, so competed as one, and, of course began a run of wins.) I understand treatments to reduce or increase testosterone are part of the process for changing gender through surgery.
Maybe this is already addressed, I haven't checked.
My comments are based solely on knowing Soldiers. I oppose DoD paying for any medical procedures or treatment to facilitate any transition of gender. My opposition is based on cost and readiness.
With regard service by someone pre surgery or post surgery, I am neutral.

The discussion is not as Cut and dry as you state. Bottom line is that there are a multitude of issues whenever the Government modifies standards for the military, whether that be related to human anatomy or the type weapons carried on the battlefield. If an individual who served in the military and later made such a huge transition and does not support that same life’s choice in the military in itself is telling. However, as I stated up front there are a multitude of issues related to this and any other policy change that needs to be reviewed in its totality not just because it is.

Thank you for your service.

No one can speak for anyone else so I have no idea why some trans people would support the ban. I have stated on RP before that there is data to support that trans people are likely to experience depression and have a greater likelihood to contemplate or attempt suicide. I have heard others on RP who seem knowledgeable say that those statistics are not accurate. At any rate, it makes sense for the military to look into this further. With the issues we currently experience with veteran suicides, it would be reckless to allow a group if people into the military already having a propensity for that.

Two famous transgender veterans are Kristen Beck (Retired E-8 SCPO from DEVGRU / SEAL Team Six) and Chelsea Manning (Disgraced E-1 PVT who gave classified info to Wikileaks). Pasting URL to old 2013 article of former angrily denouncing the latter

https://www.businessinsider.com/transgendered-seal-team-6er-issues-scathing-response-to-chelsea-manning-2013-8

IMO, and I say opinion, but really it's closer to facts. That any person who tries to be someone "PHYSICALLY" who they are not, is mentally ill. Anyone who would allow themselves to be self mutilated to be someone their not, is mentally ill. I don't argue the fact that these people are able to physically do the job. I do question their ability in the decision making process. And please don't be mad at me if I don't call you by the gender of your choice. You can convince yourself, but you don't convince me. The military should definitely not have to pay for any treatment or procedures. Plain and simple, transgender people should not be allowed in the military. The one thing the military doesn't do or do a good job of, is screen people with mental illness before they join.

Oh the things wrong with this. 1. You have to understand the demographic. This is a very political topic that divides most. 2. Transgenders are one of the othered groups who is suppose to be liberal. In today's political atmosphere, breaking away from Dem. Party is a death sentence for you in your circle of dem. Friends. 3. The biggest supporters of trans are other trans. So goong against the feelings of that group will take away a huge support system. Again, thanks to today's divisive political environment

You should have to have undergone the full proceudre and be stabilized to serve. There are many females (some males too) that have experience MST while serving. This percentage is much higher than the percentage of trans individuals. MST is considered a line of duty injury. Rooming a female who has experience MST with a trans airman who has not had the full change could further harm the female that has had the MST. In my opinion once they have had the full changes top and bottom and are stabilized with their hormones I have no problem with trans people serving. This is like requiring other medical conditions to be corrected first before allowing someone to join. To the “cost” issue my plan would be to allow the airman to take a “sabbatical” where they temporarily leave the military for a couple years to get it done and get them stabilized then return as the other gender. My biggest issue is with the people who take a few pills, leave their bodies intact in their previous gender and call it good. This could have a seriously negative effect on a service member who has experienced MST in the past and is forced to room with them while deployed. If you are going to be the opposite gender be fully committed and go all the way!