This seems like a UX/UI failure on the part of the coffee shop if he has to intervene in the customers' experience. The coffee shops I go to do a good job of making it clear what kind of customers they want by virtue of the experience you have there. This weekend I encountered the first coffee shop I can remember visiting that lacked wifi. I looked around and saw nothing but groups of people in conversation. Other shops I'm a regular at never make it awkward for me to sit there...whether with just a cup of coffee or a steady stream of drinks. If there's an outcome you want with your space, there's probably a good way to configure it so that you meet your end goal.