Why didn't Kevin go to jail after they aired The Office documentary?

Kevin just says that what Martin did (insider trading) sounds a lot like what he does every day. That's hardly hard evidence, and Kevin is a bit... slow, so he might've misunderstood what Martin was saying in the first place (despite explaining it 'three times'). I doubt anyone would pursue this 7-8 years later, after Kevin was no longer working there, on the basis on something goofy he said.

Creed, on the other hand, faked his own death to escape the police that's after him for past crimes of a serious nature like dealing drugs, trafficking endangered animals and stealing from the military. That's much more serious than a confused accountant who neither the police nor Dunder-Mifflin would care that much about anymore saying one odd thing in a very long documentary series. (Also, remember that the documentary only airs over 'nine nights in May', so it'll be heavily edited from an immense amount of footage, even moreso than the roughly 75 hours we saw. It's possible this scene isn't in there at all.)