I don't want to pass judgment on whether Google (or in the previous case, Facebook) was in the wrong, but it doesn't sit well with me that Apple wields so much power on what software their phones can run after it sells them. You may very well think that they're using their power sparingly and benevolently, but who is to say that will be the case next time around?
So far they have used the power sparingly, at the end of the day it could have been a cute cat app and did nothing wrong but it still broke Apple's terms that these companies agreed to and Apple acted accordingly.