I agree with most of what you've posted but I don't think it does legitimise Trump, who I think you mean by "the scum". Used by him it's a sign of him losing the argument, the inability to debate, but ultimately a bullying tactic of someone with power who can close down questions he doesn't like. Nobody should allow it to be the final words of any discussion. Maybe it should be called Trumpian Fake News. Or, pile o' pish.