Ah, the authoritarian. You can choose any colour you like, as long as its the one I like approach  

Let people choose to opt in (help bitcoin), or opt out (this stuff creeps me out).

IP addresses are poor for locating people to within a few miles.

Mobile SPVs have a far better gps style location system this is accurate to within a few meters, for those that hit that opt-in button.

edit:

So you can choose

> I'm buying drugs today and then visiting a stripper. I'll opt out.

> I'm buying beans today, who gives a shit who knows that. I'll opt-in and help Bitcoin