Funny we’re talking about this, after all these years, in a nation where the Commander in Chief (though I prefer that position be filled by someone who’s served) is a civilian by design, whose founders recognized that the decision to go to war was essentially a political one, vested in our representatives, not the military.
I assume Rush wasn’t anxious to go (I’d bet he had the option to try surgery, and come back), which doesn’t make his condition illegitimate. MHT and wardaddy touch on what I think it the most important factor, this was probably occurring in 70-71 during the drawdown. Didn’t need as many bodies, and why “buy” one with a medical condition the military would become responsible to treat.