If party A doesn't like party B, then that gets settled for a ballot box, but for any public event if voting for party A, openly supporting party A, and being in party A disqualifies you from participation - well, either it's a political convention for party B or the policy is simply unacceptably wrong.
I mean, there are two parties in the USA with a roughly comparable amount of supporters, with some shifting back and forth over the years. If the presence of a roughly half of population makes someone uncomfortable that's... interesting but inherently they have as much right to be there as you do. The right to swing one's fist ends at the other's nose; and the right to dislike members of an opposing party ends at the point where you kick them out from non-partisan events.
IMHO a simple test would be whether you'd consider the equivalent action appropriate for someone wearing an Obama CHANGE hat back in 2008. What's good for goose is good for gander - we can hate certain policies, we can hate certain politicians, but applying that hate and exclusion to all the supporters of these politicians crosses a line that puts it right in the same ballpark as hating a major group of our (!) population because of their race or gender or religion.
Active supporters of Trump are just as valid part of USA population as any other major group, like it or not. It's appropriate to try and convince them to change their opinion, but it's not appropriate to require them to change their opinion or try and exclude them from society.