Look, you don’t need a JAG officer on standby to know you’re not supposed to open up on a crowd of fuckin kids.

Agreed, but the order is not always so clearly unlawful. You pretty much do need a lawyer on standby to challenge violations of Posse Comitatus. It is the servicemember’s duty to refuse to conduct domestic law enforcement activities like deportation, for example, but they can be required to support those same activities in other ways.