First of all, yes, I think most people would be unsure of whether or not they are expected to tip in that situation. Second of all, "standing up for yourself"

First of all, yes, I think most people would be unsure of whether or not they are expected to tip in that situation. Second of all, "standing up for yourself" would be verbally nudging the customers as to whether they wanted to tip or not, as he did. Publicly tweet-shaming them is, in my opinion, something else entirely, and not worthy of receiving any kind of support from the owner.