We may be able to prove it. The evidence that he faked it may be overwhelming, but he will NEVER say that.
If he admits he took something to which he was not entitled and then used that as the basis to bug out in the face of the enemy leaving his unit there to fight that same enemy, he might even lose some crapweasel dems.
I'll do you one better. I'm no expert, but if he defrauded the military into awarding him medals, and used those medals to leave the theatre, he may qualify as a deserter.