I would suggest than to have him talk to the det. CC.
We are no longer talking about a cadet just coming in, but one with military experience, I doubt many on this forum know that bridge. I doubt anyone on the AFROTC side knows it, except your DS.
The question now becomes what he wants to do in the AF?
His academic career is plotted and he has filled all the squares with X's. His military career as a member who served AD has filled some more squares...doubtful he will go SFT, but not all of them.
So now I think IMPO opinion, throw it in a garbage can, but I think you are really asking about career not ROTC.
AFSC is based on a lot of things, gpa, TBCM, AFOQT, PFT, ECs, det recs, etc.
You stated he is a Physics major, most scientific majors want UPT. Is that his goal?
If so, what is his gpa? AFOQT? Has he any flight hrs for a PPl? All of that matters?
What is his PFT score?
For AFSC, it is a whole picture regarding the whole candidate. They meet a board, and the items I stated, gpa...det recs., will be placed into an equation. Highest score wins top choices.
Thank your DS for serving and being willing to serve even longer. Without you and your family's sacrifice we all as citizen's would be hurting.