Issues at another of Musk's businesses that rely on government funding.That could be a big problem for Musk if he loses his darling status with the bureaucrats that fund him. Those same bureaucrats serve at the pleasure of the unions that put them in office, and the unions are hopping mad now. If Tesla just has to pay fines, they'll probably be OK. If they are forced to become a union shop going forward, that could be a problem.
Politicians will have to play this carefully. Many won't want to go on record as being against the B1 visa program, and therefore "anti immigrant". They may make the calculation that the union vote won't jump party no matter what crap they are forced to eat.