See - this is the type of thing that riles my nerves. There is only one assumption that can/should be made, and that is because I would have edited several signatures at this point - that I am not ok with it. That is my opinion.
Your conclusion that Mods look the other way is a unqualified assumption. If we have no means of correcting the problem, then we are not simply looking the other way.
It is not an ethical matter, you should likely invest some time into looking up ethics before you make such a broad claim. It seems to be a contradiction, however, which is the more appropriate term to use. I believe the official rules and terms of service indicate we can use language that was used in Ghostbusters, and also requires registrants to be of 13 years of age or older. That implies a PG-13 standard not a PG standard. And using language found in the movie, you can get away with talking about a wide array of things.
That said, if I could edit signatures I would.