In non-pandemic times I'd recommend focusing on irl discussions because written ones are low resolution and it's hard to correct someone without it being very public, personal, and putting them on the defensive. Unless it's something heinous or alienating for people in the org (id pol sounds like it could be).

But we don't really have that luxury in pandemic times. In that case, assume everyone is acting in good faith, firmly disagree, and offer to have a chat about it. It's important to be welcoming while also drawing a clear line on some topics. Provide the opportunity for correction without embarrassment until they make it impossible (some people will). Then there is no option but to cleanly disagree and attempt to shut shit down.