Therfe is a difference between discouraging patronage and refusing it.  IMO, even if the proprietor had specifically refused service based on someone's supporting Mr. Trump, I don't think it would typically be illegal.  Here's a link to an excellent article addressing this very question......well worth reading.  Gary Crum   https://www.washingtonpost.com/news/volokh-conspiracy/wp/2016/11/25/can-businesses-refuse-to-serve-or-employ-trump-supporters/?utm_term=.5ba2a513bb27