I got this announcement, too. Thinking about it a bit, I realized a couple things:
1. The user has to know who has guns, or it's pretty useless as a tool for the anti-gun brigade.
2. You could, I assume, get the app and see if you have been "targeted." If so, geo-tagging every home and empty field makes any information from it useless to an anti-gunner or thief.
At least that's my take on it based on my current understanding.
Richard