The professor in question is a law professor, specifically he deals with securities law.

Nitpicky detail are what that area of law is all about! A newly minted securities lawyer will spend his first few years proofing corporate filings (e.g. an offering document) for the tiniest of mistakes, some of which could cost the client millions of dollars if not found.

While it might not be the greatest tactic for professors in general, it is a great idea for this particular professor.