Sounds like this company is using the words "performance fraud" to describe the employees they're firing to avoid having their unemployment insurance rates raised.
If you have over 100 employees who are non-productive and decide to keep them for another two months, that screams poor management and also that it's a bullshit excuse for wholesale firing.
If I were one of the fired employees, I would be applying for unemployment benefits and if denied, complain to the State labor board about 100 employees, all let go simultaneously, for the same thing. It sounds like the company is trying to commit fraud.
If OP has any hard evidence, he should forward it to the State Labor board for them to investigate if people were wrongly denied unemployment benefits because this company committed fraud by claiming it's employees committed a firing offense that apparently can go on for two months after it's identified.
If you're getting fired for performance fraud, you are 1) lucky they're using the term "lay off" and 2) undeserving of notice, let alone 60 days pay where you still lie about how much work you do. Come on