He can believe anything he wants, just like anyone else. But I’d imagine if you were saying the same things, your employer would be questioning your behaviour too, as odds are it would have an impact on your co-workers either directly or indirectly.
The rest of the league’s religious players can refrain from doing or saying anything publicly, why can’t he?
And that’s even on the assumption that every player of faith agrees with those particular texts and teachings.
Israel wants to earn hundreds of thousands of dollars? He can keep his trap shut until he retires, then go nuts.