Frankly if you are accurate in describing American military personnel as 'federal property', that would axiomatically imply that as slaves of the state they have no actual rights for the duration of their contract, only certain privileges bestowed upon them by their master (who can of course revoke said privileges at will), certainly including the UCMJ. If that were actually the case then the question of how to get rid of far-left rot in the ranks suddenly becomes a lot simpler to answer - a sufficiently hardline SecDef & generals can just write up a list of anyone they think is a commie and have them shot, no question asked and no trial needed. Looking through their Internet history would basically be an optional afterthought, and very far indeed from the worst that can be done to them in that case.