Earlier quoted context omitted.
A ton of games do this and it is incredibly annoying. I don't want to download an update, then have to download an update. I only wish the same restriction applied to my Android device.
Google definitely forbids self-updating apps on Google Play. But I'm not sure how well this is enforced.
Although those updates never trigger the Android update service, so I'm not sure if they are just downloading more resources of if they are able to request new permissions(I would like to assume not.)