I'm out of the loop, what did the SCOTUS do now?

Bad example. The cases where businesses could refuse service to a customer were due to religious freedoms guaranteed by the Constitution. Not liking Trump would not fall under that category. Not sure about the other example though.

In general though, I think this would be fine. As long as this business is not funded or supported by taxpayer money.

The more I see news about the United States the less I'm surprised

Ugh should have read "no sales to trump supporters or religious nutbags. Whoops those 2 are the same thing"

I don't have an issue with any of this. Private Business owners can sell their products or services to whoever they want. Don't see what the big deal is. If you don't like it, there's plenty more competition willing to take your money.