I would argue that this form of disclosure is ethical in the face of Microsoft misbehaving. It's like mutually assured destruction - and in this case (it sounds like) Microsoft tried to cheat and thought they would get away with it.

Feeling consequences are how they are kept in line. Maybe next time they will think twice before (allegedly) treating a person like they did here, as well as the creative reasoning I recall them using in the past to reduce payouts.