It’s not the NBA saying he can’t play - it’s the city/state government. That’s who he’d have to sue.
If he's still getting paid even for the games he can't play, then he may have no need to sue the city/state government.
The NBA and/or the Golden State Warriors should be suing the city/state government in that case, since they're the ones who would be taking the financial hit for this lunacy.
Yup. The NBA refused to mandate players get vaccinated.