Earlier quoted context omitted.
There isn't a law on the books prohibiting hardware stores from selling knives. There is a law on the books prohibiting publishers from publishing descriminitory ads, even if they didn't write them. That's the difference.
The difference is that the law shouldn't even be on the books imo. The person discriminating is the private property owner/manager they engaged in the advertising. Facebook did not.
I'm trying not to say anything too mean, so I'll just say this: learn some history.