I would’ve called the manager of that particular store first. Weird situation. Wrong of the guy to be so intimidating/threatening. Makes me wonder if he was on something–because who treats customers like that?
(Once my 20something D was intimidated by another customer at a gas station–he begged D to pay for his gas with some sad story and was a very large, threatening guy who wouldn’t take no for an answer. She was scared and her 4 younger sibs were in the car waiting for her. So she used her credit card to pay for his gas. It was in a bad neighborhood where she shouldn’t have stopped, but she was not familiar with that city. She didn’t call police. Basically, I thought of it as a charitable donation. Like the OP, she paid “voluntarily,” but only because she felt threatened.)