The problem is that "Unix" can mean two things. It can mean an OS that is ultimately derived from Unix, and it can mean certified compliant with the UNIX standard. Neither meaning implies or requires the other. MacOS is both of those. In fact I think it may be the only operating system derived...
leo @'d me in a thread about his last dream, stating he was passionately making out with a guy he used to know and then woke up while reaching for his crotch, and said that i would "know who 'tf' it is"
and of course i know, it's luke