First, congratulations on getting iOS approved!
The silver lining is you now have an awareness of the misuse of Community Content by these clan chatters.
Now, clans – I realize they are customers and you don’t want to “talk down” to any subset of customers. But honestly, this is low threshold behavior. I have seen Yahoo! Avatar and Widget (remember those?) forums shut down for the same behavior. Warnings were given, not heeded, and there was no other alternative.
In my opinion, there is no dialoging and working with such folks. They are like graffiti taggers, looking for blank walls to vandalize. They don’t simply listen, go off to Michael’s, and buy canvasses to paint on. They find another unguarded building/wall to tag.
These clan chatters are very likely not visiting and reading your blog, else we’d see them spamming the comments!
Their M.O. is to take advantage of easy routes to communicate. They are not motivated to make any effort to facilitate their own actions in their own space. I hate to be pessimistic but I truly do not believe we will see this. I doubt any of them will ever hear of your suggestion, as they lurk simply in their comfort zone, the freely accessible Community Content within the app’s UI. Like parasites, they have no reason or interest to leave.
So, leaving CC access the same, likely we will just get another buildup of clan cruft.
My suggestion is, you leave it and add a second CC with higher barrier to entry such as being a WP member, that can be used to log/block offenders. I think you’ll find the first CC fill up with cruft again. At that point they have had their warning and chance to change, and if it must be removed for iOS approval of next version, so be it.