In this comment I meant a public venue in the sense of any venue not specific to a particular political party or some members-only closed organization.

Sure, it's legally free to do as it chooses, but I'm claiming that it shouldn't choose that way, that all such venues should explicitly allow also people who are advocates for the "enemy" party if this is not a political event. "The society", whether talking about the whole country or about the tech domain or about particular narrow industries, inevitably includes people of all parties, including active Trump supporters. They're part of the community. Where do we draw the line if supporting one of the major presidental candidates is not acceptable? Do we start labeling tech cons as "Democrats and other anti-Republicans only" events? That seems really wrong, that's putting way more politics in tech events than should be reasonable - IMHO they should actively choose to be politically neutral.

And I believe that it's important to underline that this is a symmetric thing. Yes, there's a polarization where many people believe that the active supporters of the other party are inherently unethical. That cuts both ways, and has done so many times in past. If you say that it's okay for niche industry conferences to kick out someone for openly supporting the presidental candidate they like, then it means that it's okay for niche industry conferences (now or after a couple elections) to kick out people like you for openly supporting the candidate that you prefer. And I don't think that this is where we want to go.