They don’t need to do any of that. He has made himself unavailable to the team. They haven’t breeched anything. He is functionally sitting out. This is what happens when you sit out.
No he’s not made himself unavailable, he’s willing to play and practice he’s being denied because of a government mandate, he’s not holding out for a new contract and he’s not the only NBA player unvaccinated and no one else is being treated this way