I can see the community disagrees with me, which is fine. It just gets very old to see so much uproar over an IMHO completely standard App Store rejection. The rule makes complete sense to me (they don't want you using their App Store to point to competitors), and nowhere is Apple saying apps are not allowed to support Pebble - Pebble itself has an app!
Now, if Apple decides to remove Pebble's own app from the store, that would be a reason for some justified uproar...
The purpose of the application description is to describe the features of the application. If your application has Dropbox support then I think you'd agree it's perfectly reasonable to mention Dropbox in your app description. The Pebble is an iOS accessory. It's equally reasonable to describe Pebble support as a feature. This goes beyond simply not mentioning competitors; Apple is preventing developers from describing features of their iOS app. It might be the same rule, but it's being used quite differently and worryingly.
Some apps only exist as companion apps for the Pebble, what are they going to put in their description?
Now, if Apple decides to remove Pebble's own app from the store, that would be a reason for some justified uproar...