I tried to respond but got spammed. So I'll try to sum up
I don't understand why an adult wouldn't buy a cup of coffee if they are using the table? Then get surprised when they are asked to leave?
I guess the question is, why were they asked in the first place? I've honestly never even been in a Starbucks were employees approached patrons, or even really came from behind the counter. According to the link I posted above, the two were there less than 10 minutes before cops arrived. They really weren't even given enough time TO loiter.