It's not enforceable in the same way that having all your apps removed from the app store isn't actionable. Anyone engaged in commercial development for the iPhone only does so at Apple's pleasure, which may be revoked at any time.
Of course, if this causes your users to seek refunds and you have already spent your earnings, that could get problematic.
Of course, if this causes your users to seek refunds and you have already spent your earnings, that could get problematic.