He deserted his post, that is not in doubt, nor is it even in question.
He should not even be getting a faint HINT of back pay for that.
It may not be in doubt, but he has not been convicted. The courts martial may very well order that he surrender all back pay, but until then we STILL have a presumption of innocence until proven guilty. Or would you like to change that and force people to prove their innocence?