I don't understand how it is possible that Stripe is not allowed to have this functionality but Square is. Certainly Square does not give 30% to Apple for every swipe.
The cross-platform bit is interesting though. This should send a clear message to developers that they should go with ANDROID FIRST.
The rule doesn't apply to either. It specifically refers to in app content and features. Accepting a credit card for a good that is not "in app" (ie. a physical good like coffee or a virtual good like consulting) is perfectly acceptable under the rules. The reviewer in this case is just being retarded.
The cross-platform bit is interesting though. This should send a clear message to developers that they should go with ANDROID FIRST.