What code under UCMJ permits an Article 15 for having a service animal with you in barracks while packing up belongings?

Not enough info to make a statement of support or condemnation. Any one one who has taking what limited info here and making definitive statements of "Thats illegal" "The CofC is wrong" ect ect ect is just farting in the wind....

I very much doubt the incident and CoC decision to punish happened as suggested in the title...
there is much more to this story that is not being told here...

And then more info needed...
-Has this Service member previously been told the animal is not to be brought in to the barracks?
-Was this the first time the animal has every been in the barracks?
-Has the SM been told previously when she bought the animal into other on post buildings, the animal was not allowed?
-has the SM been counseled previous to this incident about her animal, causing issues, barking, fighting, \aggressive, defecating or urinating in inappropriate places?
-Is the animal a "service Animal" Trained for a medical issue, adaptation or assistance, to which the person has a valid medical need? Or is it a emotional support animal, which DOES NOT have the same protections / rights of a service animal under ADA.
-Was the barracks in an area restricted from domestic animals? Service animals?
-Does ADA apply to a US military installation? If you say yes, provide a cite that supports that. I have not seen a barracks yet that is ADA compliant, perhaps there are some that house wounded warriors ...I don't know about that. It is reasonable to assume, barracks for active duty SM are not required to be ADA compliant seeing as medical issues that fall under ADA likely are not compatible with military service.

For reference and understanding
Service dogs and emotional support dogs

Service dogs

A service dog is a dog trained to do specific tasks for a person that he or she cannot do because of a disability. Service dogs can pick things up, guide a person with vision problems, or help someone who falls or loses balance easily. For example, a service dog can help a blind person walk down the street or get dangerous things out of the way when someone is having a seizure.
Protecting someone, giving emotional support, or being a companion do not qualify a dog to be a service animal. To be a service dog, a dog must go through training. Usually the dog is trained to:
Do things that are different from natural dog behavior
Do things that the handler (dog owner) cannot do because of a disability
Learn to work with the new handler in ways that help manage the owner's disability
Because the handler depends on the service dog's help, service dogs are allowed to go to most public places the handler goes. This is the case even if it is somewhere pet dogs usually cannot go, like restaurants or on airplanes. But there are a few exceptions. For example, service dogs can be asked to leave if they are not behaving well.


Emotional support dogs

An emotional support animal is a pet that helps an owner with a mental health condition. Emotional support dogs help owners feel better by giving friendship and companionship. These dogs are also called comfort dogs or support dogs.
An emotional support dog does not need special training. Generally, a regular pet can be an emotional support dog if a mental health provider writes a letter saying that the owner has a mental health condition or disability and needs the dog's help for his or her emotional support.
In most states, emotional support dogs do not have special permission to go to all public places like service dogs do. But, emotional support dogs are sometimes allowed special consideration. For example, the owner may be able to get permission to have an emotional support pet in a house or apartment that does not normally allow dogs. Or, the owner may be able to get permission to fly on a plane together with the dog.
To get special permissions, the dog owner needs to show a provider's letter to the landlord or airline. Sometimes, the landlord or airline will also want to see information about the provider, such as a copy of their professional license.

Something else is going on here. I have never seen a CoC just punish people for seemingly no reason at all. Typically there is some egregious infraction or a pattern of misconduct. Remember, it's a chain of command. Chain being the key word. It isn't just some guy making a bad decision. Several people would have to agree with and go along with the same bad decision. Can it happen? Sure. Is it common? Hardly.

Sounds odd at best to me, I know an officer who was seriously injured in an IED incident during a route clearance mission who while nearly blind was retained on active duty and has even deployed since the incident. The guy is awesome. He has a service dog that accompanies him and is a well disciplined and great animal. Because of the dogs special training and skills and it having been prescribed for him it gets to go everywhere.
I think there is a lot more to the story than is being told.
One question that I have is;
Is the "Service Dog" an actual trained and for lack of a better term certified service dog or just a dog that the Soldier has that makes them feel better.
There's a big difference in helpful to have, verses actually getting a prescribed animal.