Unfortunately, California just changed this, and such a clause was enforced against Damore. I think it's a terrible trend and basically takes worker rights out behind the shed and shoots it in the head.
The only reason they wouldn't do this is if either a) Chevalier didn't have such a clause or b) they're going easy on a troon.
California is the most ass-backwards body of government I've ever seen. I agree with you on arbitration, and I think the reason why they're going easy on this troon is because they were partly responsible for the moral outrage that got Damore fired to begin with, if I had to guess.
Imagine if those details were to ever surface.