to be honest, i think the ban on non muslims eating is unnecessary, because in essence fasting is about resisting temptation, and choosing to fast for god, and to suffer as those who are less fortunate suffer. If you are eliminating the temptation, then you're kind of going against the whole point. However, i have in the past seen some pretty inconsiderate behavior of non muslims chomping away infront of those fasting, which is pretty bad. I think, it shouldnt be an official rule, but that people should just be asked to consider other peoples feelings, or beliefs at a time like this.