I wish him the best. First and foremost his health should be his priority. As stated he must be off the meds and an IEP for quite sometime.
DoDMERB will Q or DQ according to the requirements set forth. The commissioning source will decide whether or not to waive that DQ.
~ IE USMA may say no, but AROTC may say yes. They are both under the Army umbrella, but they are different commissioning sources.
~ Same is true when you look at ROTC. AFROTC may say yes, and AROTC says no. Both ROTC, just different commission sources.
Just my opinion, but I think you should also place into the equation, what schools he is applying to for college. If he applies to an SMC (TAMU, VT, VMI, UNG, Citadel, etc) he can be in the Corps without being in ROTC. However, he cannot be in ROTC without being in the Corps. That equates to a lot more time management as a freshmen. Same goes for the fact if he decides to attend a university that is not the host ROTC unit. It means he will be a xtown cadet/mid and have to travel to the host unit at least 2x a week, again time management will be key.
Good luck. Thank him and your family for wanting to defend this great nation.