Yes, combat veterans often suffer from PTSD, but what about Russell's plights? After all, watching your buddy get blown to bits by an IED is practically the same thing as having your song rejected by a celebrity's agents.
I love the implication that he had a choice between combat or college. If he was allowed into the military at all (which, sadly, is almost certain) he would have been put in a supply role. He can't move his eyes and he's difficult to understand, he would have been a liability in combat.