That's just your opinion. You are creating facts not in evidence. According to the facts as presented, he was just a shopper looking to buy a product that happened to be wearing a Trump shirt. He was attacked for it. Are you saying that if I go shopping in a Trump shirt that I'm trolling for trouble. If so, then go screw yourself. The last I looked, I still live in America and am entitled to wear apparel that supports the President of the US without being attacked for it.
If you are shopping in a Trump tee or hat and you get grief find another store. If you decide to scream back at the clerk and record it for YouTube then you may be a troll. I guess that’s OK the Construction grants you the right to be a jackass.