The question is what will convince individual troops and units that their orders are illegal. Disobeying orders isn’t something the military takes lightly. In theory a court order should be proof enough, but who knows these days.

Normally yes, but the president has the power to federalize National Guard troops in extraordinary circumstances. That power hasn’t been exercised since 1965 though. Until now.

ICE refused to produce a warrant, so this wasn’t an arrest, it was an abduction. The folks who were charged for trying to stop it were acting in defense of others and ought to be acquitted.