If changing their baby's diaper in the restaurant was against health code violations or if Starbucks has a rule against such a thing, they should have been politely told so. It's the employee's job to be courteous to customers. Is it a gross thing to do? Yes. I'm a total germaphobe. I won't even directly touch a bathroom doorknob. But people are more important. How hard is it to kindly ask them not to do that in the future and then, when they leave, walk into the backroom, grab a bottle of disinfectant, and then go to town on that table? I used to work at a Starbucks, and our manager never would have put up with an employee being anything but kind to a customer.