Not saying anything about hanging out with thugs, but I'm not sure about Leonard being uninvited.
According to a guy on Finebaum the other day that claimed to be a friend of Leonard's, they both have a mutual friend that lives in those apartments. He said that he wasn't there that night, but he had been invited and that both of them had been to parties there before.
Again, this was a caller to the Finebaum show, so I don't know how much validity there is to it.