No, the previous commenter is saying that you cannot trust the identity provided in commits period. This has nothing to do with trusting employees, rather placing trust in the identity in commit.

This is true in general internet, but workplaces are normally more high-trust. If one needs to guard themselves against hacking by their co-worker, they have less time and energy to do actual work.

So a fiction character is maaybe OK, as long as it is clearly fictional name and no one else in the company does that; but other stuff, like actually impersonating other co-workers would be very bad, and should eventually leave to firing.