Lawyer here.
Some of those cases are about the NLRB's authority, not anything else. I didn't look up all of them.
Past that so, as far as i know, attempting to waive class arbitration is untested against an explicit state policy, and i have doubts it would survive.
The only case about this so far is whether class action arbitration waivers are enforceable in general in the face of it being "too expensive" to arbitrate individually (no state law, etc, was at issue here), and the answer is "yes, they are enforceable". This is not surprising, these kinds of straight policy arguments rarely are winners in court. A state law would instead be a preemption issue.
It's one thing to say "you must arbitrate", which is clearly covered by the Federal Arbitration Act. That is why state laws that attempt to ban such clauses are preempted.
However, there is nothing that i'm aware in that act (though admittedly, it's been a while since i looked at the act), that preempts state laws prescribing the form of arbitration.
Thus, a state law saying "arbitration is awesome, but banning class arbitration is against our public policy", if they exist, should be valid. Preemption must be very clear.
Again, it's been a while, but when they were first preempted, states mostly did not have such laws on the books (IE they found required arbitration to be against public policy, and that was preempted by the FAA. They did not have laws that said that banning class arbitration to be against public policy)
Of course, if someone knows of a part of the FAA that explicitly allows prescribing the form of arbitration, then yeah, everyone is gonna lose.
Funny story: most of the places that pushed so hard for required arbitration had clearly not thought through the consequences. They still haven't, AFAICT.
I remember having lunch with one of the counsel at EBay and some other companies about a year after the original supreme court ruling on class actions, and he was very happy they could require arbitration (they got a lot of nuisance suits, to be fair to them), and asked me why Google didn't require arbitration (Note: I'm not legal counsel for Google, i haven't been involved in Google's TOS in years, blah blah blah)
I pointed out that class action/courts generally at least required a licensed lawyer to maintain and work on the suit, which was expensive, whereas arbitration could be done by lay people, and that he was essentially betting that nobody could make it cost effective to have a paralegal or someone manage fifty arbitrations at once, or a class arbitration.
I suggested that was probably a bad bet.
I still believe it to be a bad bet.
(It hasn't changed a lot because the other side of this is still fighting to the death instead of considering new business models. They are very much not used to dealing in volume)