> So long as I can get a "STFU and leave me alone" button.
I think you are missing the whole point. (but don't worry; it seems like pretty much everyone else is too, judging by the articles here and on the beeb, and by the tweets copied on both)
The badge is *inviting* chat, not trying to force it on anyone. If someone is wearing it, they are hoping that someone will see it and talk to them. They aren't wearing it as an excuse to arbitrarily start talking to people who aren't wearing one.
If you don't want anyone talking to you, that's fine -- just don't wear one and carry on as normal.