Valid concerns about op-sec and personal responsibility aside, I think this is another example of why "security at the expense of usability comes at the expense of security". Official DoD communications equipment sucks, so people use the less secure, more usable encrypted communications platform when they feel they can get away with it.

Maybe the DoD should work on developing some internal Android and Signal forks that focus on adding additional critical security controls without impacting usability. There's an obvious desire path here.