I suppose there's probably a bunch of legalese to prevent that though...
If you are ever going to sign an employee agreement that binds you, consult with an employment attorney first. I did this with a past noncompete and it was the best few hundred I ever spent: my attorney talked with me for an hour about the particulars of my noncompete, pointed out areas to negotiate, and sent back redlines to make the contract more equitable.
They’re great partners when confronted with this kind of contract. And fundamentally, if my adversary/future employer retains counsel, I should too. Why be at a disadvantage when it’s so easy to pay money and be at even?
There are some areas my ethics don’t mesh with, but at the end of the day this is my work and I do it for pay. And when I look at results, lawyers are the best investment I have ever made.
But even without that, judges have huge amounts of leeway to “create” an ex post facto contract and say “heres the version if that contract you would have agreed to, this is now the contract you signed”. A sort of “fixed” version of the contract.
Severability clauses themselves are not necessarily valid; whether provisions can be severed and how without voiding the contract is itself a legal question that depends on the specific terms and circumstances.