NBA players are more like contractors than employees. Let's say you're the best damn plumber in town, but you're also a virulent antisemite. There are some people who'd bare it and listen to him rant about "the globalists" because they really need their pipes unclogged, and there are people who'd rather go with a second-rate plumber who's not a whackjob. People can choose not to support the antisemitic plumber just like they can choose to boycot the nets.