I think he's referring to how they are arrogant for threatening them, sending them "design tips", and playing themselves up as sexy and dangerous all in the same message.

They definitely have a valid point about the plagiarism but they're being really cocky and showy about it.

Edit: Ya, they might have been trying to be funny or venting, I can understand that. But they really shouldn't have ANY kind of physical threat in there at all. Its childish and just pointless posturing.