To clarify, in some jurisdictions in the US, businesses cannot represent themselves. Which is a travesty for companies like this guy, who doesn't even have that as an option. I don't actually know about patent law, I just have had an experience with a frivolous lawsuit for a low-ish dollar amount that it would cost more to defend than lose. Because we couldn't represent ourselves, we just had to let it go to default judgement.

DO NOT do this. You probably also should have used a throwaway account and provided a lot less detail on the scenario. If your adversary finds this post (they likely will) your position and options are at a significant disadvantage.

OP would have to spend tons of money and hundreds of hours fighting this, then still have a nonzero chance of losing and going out of business. Always easy to say that someone else should fight it.

Basically telling him to do anything else is to request of him to do the policing of anti-social behavior in a broken system that enables it, at huge personal cost.

Some people do. People like that are necessary. But not everybody is willing to take that responsibility and associated burden.

This is bad advice. OP is trying to start/run a business, not fix the world or satisfy somebody's justice quest. It's nice to do if you can, but your first responsibility is to yourself.