re: What would happen if MAGA blocked the highways in protest of this trial?

They are almost certainly violating one or more misdemeanor statutes, and every protester SHOULD be prosecuted. But it is must a misdemeanor. I doubt that would care. Pay the fine and feel like a SJW.

Maybe they should be certified as class-action defendants and face liability for every single individual inconvenienced or delayed by their foolishness. THAT might involve some serious scratch.

If every ... individual ... blocking that road were facing joint and several liability for millions of dollars, would they be blocking the road? I think not.