Is this about severance pay being held hostage to NDA's and no future litigation over H-1B or other worker discrimination actions?
Generally speaking, a "paycheck" in its common use is in exchange for services rendered. "Severance" is supplemental pay to compensate a long-term employee for sudden loss of income, usually to cover household expenses until other employment can be obtained.
Linking severance pay with waiving of rights is a de facto signing a contract under duress. If the issue is that workers signed the contracts under duress and now have regrets, then you might get away with saying that a contract is a contract.
For the workers who did not sign the contract but still demand to sue for severance, that's another matter entirely as there is no underlying contract.
-PJ
-PJ