If it's not a joke, it's at least an exercise in absurdity.
I wrote a regex that would allow things that aren't facebook, and then you said "No, you're not allowing things that aren't facebook, you're not allowing things that don't match not being facebook".
If it's not a white-list, it's at least an opposite-of-black-list.
If you think you need a blacklist you should probably be using a whitelist. If your problem can't be solved with a whitelist then it's probably better solved in a way that doesn't involve a blacklist or a whitelist.
That regex will only positively "match" non-facebook items, and will only block facebook if implemented in a whitelist.
I'm just playing the straight man to your joke. Of course it's functionally a blacklist: That's what you asked for.