Good news for Pebble and iOS users: Pebble has just posted on Reddit that it is working with Apple to make sure that rejections like this will no longer happen.
Still a work-in-progress, but we’re working with Apple to clear up any misunderstandings to make sure rejections like the handful of recent ones don’t happen again – they’re being super responsive the concerns that bubbled up (much appreciated!). Apps are still getting approved with mentions of Pebble support in the description or metadata (e.g. RunKeeper). For now, developers should continue with their iOS app update plans and approval submissions to the iTunes store as normal (i.e. include Pebble support in your app info if that was your original intent).