That's the thing about retaliation. Unless the retaliator is really bad at this, it is always going to look gray-area, because you're shading available policy to reach a desired outcome.
You want to do it that way precisely because it plays on some peoples' preconceptions, completely aside from not breaking black-letter law.
A lot of folks will see a enviable company, assume the Powers that Be must get most of it right, and assume the person they already knew was a troublemaker (they were contradicting their betters, weren't they?) was also bad at their job.