I say that not as a slag on him, but I honestly feel they did him a huge disservice in the AO debacle. Why do you HAVE lawyers? He seemed to go to Australia on a wing and a prayer, and a promissory note from Craig Tiley. Now, maybe that is naive. Maybe they did know that there could be a battle, and those Australian lawyers were all lined up and prepped. If that is the case, though, that means he was not the innocent going in, and he knew it might take attorney muscle to get him in.
As to fine points, I looked it up. After I said the guy I know (of) who was kicked out for working without a visa, (he was Canadian, btw, and it was a one-day shoot. For a Canadian company, with a Canadian crew. The Canadians are very generous about letting us in from the US to shoot there, but the reciprocation is poor...) anyway, so it made me think about the "work visa" aspect of what athletes come in on. They come on a P1-A visa, which is specific to performers and athletes, at top level, for limited engagements. I'm sure no one here believes that Novak is going to try to sneak over the border, either from Mexico OR Canada, but just to say, aside from the vaccination requirements, he needs a very specific visa to play the USO, or Cincy.