"are you guys going to buy anything? .... ok, well i'm going to have to ask you to leave. we're quite busy, and we need the seats for paying customers. sorry guys. hope the meeting goes well." - would have been the "appropriate" response. they straight up called the cops to come save them from loiterers... lol. and i've never known cops to make a situation... better.
it's like alcohol. take a bad situation, and pour cops all over it.
most of the things people call the cops for are minor things. you're potentially ruining someone's life because you're mad for 15 minutes. take a fucking breather, and stop throwing your fellow man into an uncaring & biased system.
the appropriate response you just made up in your head is what happened in real life. they were asked to leave and refused