Yes you can refuse illegal orders. But you better damn well have all your ducks in a row. Of course it’s easy for Congesscritters to encourage other people to do so. They don’t have to meet a mutiny charge.
No, this is all misdirection. These same clowns/traitors earlier said that the use of such troops is unconstitutional. So, the follow-up recommendation of sedition is asking for one of their minions to kill them.
Just like he did.