Which is fine for their store. But one of the things that used to make Android a more free ecosystem was that you could load apps from 3rd-party sites or stores, including stuff like F-Droid. Some of these apps do things that Google in particular won’t like - i.e. circumventing ads/analytics - so having them control who gets signing keys is not good
Was he though? Nobody has been arrested and charged yet so for all we know the shooter could be a jilted lover etc. might not even be a “he” for that matter