This habitual, simplistic error is a large part of why moderates and centrists are struggling. On here, it is quite often a result of people attempting to smear the forum or its users, (I'm not at all accusing pp of this, just noting the dynamic), but it seems to happen in good faith, too. People genuinely think that if one discusses a contentious issue that reveals some kind of support. As if ideas are contagious.
Actually the tacit suggestion that one has to hide or suppress ideas that aren't suited to the current orthodoxy only worsens the paranoid attempts to guess what people really mean - see all the accusations of 'dog whistles' and 'unconscious bias' - because when everyone is carefully curating their language, and everyone else is carefully scrutinising each other for wrongthink, nobody trusts each other because nobody can ever be honest.
It's not healthy. It makes discourse brittle, leaves blind spots, clears fertile ground for opportunists, and creates an atmosphere of superstitious 'ooh, she said a bad word!' febrility.
I suppose this is purity spirals, isn't it.