As they should. They shouldn’t have been arrested at all. If they refused, then let them sit there.
So if a business owner asks a non-paying customer to stop loitering and leave, and they refuse, they should just...accept it? "Sure, no problem."
You live in a fantasy world.
A business has every right to ask a loiterer to leave, and if they refuse, to call the authorities. Happens every day. Should result in an ass-whooping. A Masvidal flying knee to the jaw would be appropriate.
What policy is it that say they have to purchase at a star bucks in order to wait. Show me that.
They actually changed their policy as a result of this incident. You can now hang out at a Starbucks without purchasing anything...that is now their policy.
Only in your fantasy world is this "right" and normal.