As far as Trump, his policies, and his behavior go, this isn't particularly bad or worth talking about. I'd rather focus on the fact that he's f**king over the poor and working class and apparently trying to start Iraq 3.0 in Iran. I think liberals often spend too much time attacking Trump as a person and not enough time attacking his disastrous and vile policies.
You're not wrong (except on the part when you say it's not particularly bad. We have slander and libel laws for a reason). But we shouldn't be tolerating this sort of behavior. Actions like this only pump more adrenaline into the Deplorable base.