Should an Officer who was non-selected for promotion, and discharged at 16 years of service, reenlist to finish their 20?

Yes, why not? Getting passed over isn't always fair, objective, or justified.

Suggest checking out availability of warrant spots before hitting the enlisted spot. Works well if you are eligible, if not definitely try the enlisted.

Yes. At some point, your retirement will revert to highest rank held.

I was a 1LT that got caught up in the downsizing, Graham- Rudman and deactivation of the unit I was in. 1989, just before Desert Storm kicked off. My record was good, but hundreds were getting the boot. Long story short, I enlisted, hoping to finish up my career. Yes, it makes sense because you want those years to count for something.

You could become a government employee and buy your time back into their retirement.

You could I guess. I went to the reserve, got promoted and finished my active time.

First, the person in question must needs apply for an upgrade of discharge; Things change. If one is not required, this person should get a physical fitness test and phycological.

Whenever someone asks me something like this as close as you are I tell them to look at the big picture. I frame it like this as the retired E7 that I am (currently GS). :"If I am 95 years old on 1August what's going to happen"? They look at me and have no idea what I am talking about so I repeat it. They invariably say they have no idea what is going to happen to me if I am 95 years old on 1 August. I then reply "I'm getting my retirement check". Then they understand what the big picture is. Lifetime pension my fellow service member. And with the way COLA has been the last 2 years my retirement raises are higher than the AD force. AND whatever the COLA raise is for retirement pay your VA disability pay goes up the same amount so it's like getting 2 raises. Last year 5.9%. This year probably more. They don't hand lifetime pensions out like candy in the civilian world so bite the bullet and finish it up enlisted if you have to. If I recall correctly though I may be wrong I believe that after a certain period you can apply for retirement at your highest attained rank. Regardless some money is better than no money. Finish it up. Good luck to you.

Absolutely. Be foolish not too.

Reup Chaplain. You'll be glad you did. And pay no mind to anyone saying "substandard." Such comments are substandard and unworthy. There are many fine officers, through no fault of their own, who have been downsized by the Military. It's the nature of our beast. After Vietnam massive "bloodbaths" filled with RIF officers occurred. And NCOs and lower enlisted endure the same purges. After the Gulf War, politicians sought to capitalize on the "peace dividend." After 9-11, it took months and months refill, retrain, and prepare the troops for deployment. Anyway, hang in there. If you have ten years as an officer on active duty (and you are probably at least close), you'll get to retire at your highest held rank. Hang in there, Soldier!