They would not be doing law enforcement and arresting people, they would be acting as security guards.
Same thing. It is law enforcement they cannot be used. Marines would be way better.
And like a said, you don’t have to ink movie and book rights first.
That’s part of a modern seal mission order. Assigning the book rights. Marines keep it nice and legal. Unless of course, Trump wants to declare it an insurrection, then he can use lesser units than Marine infantry domestically.