Obviously he didn't. If he did infringe, they wouldn't have sent a legal statement saying that if he complied they would "release all claims" (as they did). Instead, they would tell him to stop and in return he wouldn't be continuing "willful infringement".

Saying "do these things immediately and all claims will be fully released" is usually a sign of weakness to begin with - pretty much any company lawyer is going to open by overplaying his hand.

This is only an overplay of a weak hand.