I'm not saying Trump supporters should be kicked out of bars. If I owned a bar I certainly wouldn't kick out Trump supporters. After all, it's not like the Bernie supporters have enough money to keep a business afloat.
But this is a win for freedom of association. All interactions should be consensual. Obviously, we understand this concept when it comes to relationships and sex. But for some reason, fewer people hold consent as so important when it comes to business transactions.
You don't have to go to a bar, and a bar doesn't have to serve you.
But this does seem like quite the contradiction compared to courts forcing bakers to bake cakes for gay couples.
The distinction, in this case, is that the bar did not deny someone based on religious beliefs. Political discrimination is allowed. So you cannot deny a customer based on your own religious beliefs, but you can deny a customer based on their–and your–political beliefs. Unless of course, that customer holds a protected political belief, in which case you still cannot deny them.
Some people think that when a business opens their doors, they are waiving their right to deny service to any peaceful customer willing to pay the price for a product on offer.