I think “weird” is an interesting case precisely because it’s a subjective term. Whether or not someone is weird is in the eye of the beholder. It can also be taken positively or negatively, depending on one’s outlook. And it can be for different reasons; calling someone weird based on their political beliefs is different from calling them weird for how they look, for example. And even calling someone weird for holding one particular value is different from calling them weird for a different value.

Insulting one person for being weird doesn’t actively target anyone else because people may identify themselves as weird or not, and separately may identify it as an insult or not. It works very well against Trump and his allies because they specifically position themselves as believing in the values of the normal American. So being called weird is a doubly-whammy of undermining their self-image and being based on something that actually does make them a bad person, and so the only drive-by victims are other people with harmful beliefs.