No, it isn't. Facebook are knowingly violating the agreement, so Apple can remove it anyway. Google, Facebook and Amazon do similar stuff without warning, and sometimes without rules violations.
Secondly, Facebook are violating the agreement to do something that Apple is so big on avoiding - invading peoples privacy. They have built their company around this recently, so violating it was always going to end like this. It's like if I developed an app to screw with Google searches - Google would ban that from the Play Store straight away.
This is not an atom bomb. This is things being banned for breaking the rules. Standard practice. Facebook just thought the rules didn't apply to them, got caught and now pay the price. I wouldn't be surprised if Apple does not reverse this decision.