Makes sense. Apple doesn't want you using their app store in a way that could be promoting their competition.
For example, maybe I'm browsing the app store for new apps and I come across this app in question. Reading the description I see it says something about the Pebble watch...hmmm..I've never heard of this. Now I look it up, it looks cool, I like it, now I want to buy the Pebble instead of the Apple watch.
Their app store - their rules. Just remove mention it and it'll be approved.