I didn't say "take him to court", I said "consult a lawyer".

Any advice you get from HN is just as likely to get you in a heap of trouble as it is to work. If the time comes to enter a courtroom then obviously you will need representation, but the primary value of a lawyer is in the advice and experience you receive before even considering setting foot in court.

Actually, the law is somewhat about who is right. If he has a trademark for name that covers your space and you use the exact same name, then (IANAL) it sounds like he's correct. But you should spend some time and money to consult a lawyer. My guess is they would tell you that you don't have a case.