The standard line in cases like this (whether it's a frozen payments account, a rejected app, or a suspended social media account) is that you can't tell someone what rule they broke, because this gives too much informative feedback to actual malicious actors about how they got caught. I call bullshit. Until someone can demonstrate that this is an actual problem, I will believe it to be a fake problem, purely an excuse used by giant companies to justify their systematically hostile (and cheap) approach to customer service.