IANAL, but: iOS is not a monopoly, but it has a dominant position, especially in US (over or close to 50% market share). For tablets their market share is even bigger than that. That should be enough to at least consider some actions, on some level, by someone. Google and Mozilla could sue, I guess? On the other hand, Apple making it a security issue could be a solid defense in court, maybe that's why no one bothers.