It's not that he necessarily hides something intentionally. There are reasons why a company might want to separate from an employee. HR has to make sure that

It's not that he necessarily hides something intentionally. There are reasons why a company might want to separate from an employee. HR has to make sure that this employee doesn't sue then the company, so they're fishing for enforceable reasons. It might be bullshit, but if it's legally sound, they'll use it. I think it's a fair bet, that this employee didn't have the best standing with his superior and he might not even have been aware of it.