Technically, maybe, but effectively, nobody is going to be able to withstand BigCorp's 100 lawyers whose mission is to bury you in legal fees if you push back. By the time that you confirm these things are unenforceable, you've spent your life savings on $millions in legal fees, and possibly gone into crippling debt. In the legal system, might (wealth + lawyer quantity) makes right.

As I recall from John Akula's Corporate Law class, judges in the US tend to be sympathetic to the following argument:

"Defendant has never worked in any other industry. He has three kids. He's gotta work."

(That's for regular employees--it's a different issue with founders who may have significant equity stake and such.)

It sounds like moving to California for a year would be way cheaper.

The "bury in litigation" is overstated. Since it's the _company_ that is going to sue you, there's a limited amount of shenanigans they can do.

The worst is that they can delay the case for years, leaving you in a legal limbo. Or go after your employer, involving them in the discovery process.