Doesn't matter; it's still worth reporting to them. He could very well take a big hit to his military pay or something as a result; they get paid for a certain period of time after being discharged if I recall correctly. If he was doing this while on active duty, then he's even more screwed than if he just did this after being discharged.
There is nothing that the Army can do to him unfortunately. If he was still a Reservist or Guardsman something might be able to happen but due to him being out, the Army's hands are tied. He would only have been able to continue to draw a paycheck for a maximum of 70 days after his last day in the Army to cover his accrued leave days. I looked him up on AKO and there is no record of him so he is completely out. Unless he was using a government computer to commit these crimes the Army won't do anything. But to be honest, they wouldn't call him back to Active Duty for something that they would see as a minor crime. Piece's of sh1t like this guy make all of us Soldiers look like garbage. I hope someone does find him and beats him with in an inch of his miserable like. Wouldn't theft by deception come into play here also?