Because Waters is a Democrat, and what she calls for is mob action and vengeance. The mob lunges forward, filled with self-righteousness and seeks a dehumanized enemy.
What adds to the danger is that Trump voters have already been dehumanized as “deplorables” and most recently and loudly as Nazis by many in media and the left, for daring to think America should have control over its borders.
Trump wouldn’t know civility if it bit him. He’s not an example of prudence and good manners. And he’s no Mister Rogers.
What he’s doing is making Waters the public face of his opposition. He won’t let it go. Her idiocy has great currency.