Do you know how many people there are in the world? I have a pin on the map, and it's been there for a few months. Nobody's stalking me, because they don't know my last name (heck, they don't even know my first name!), my street address, or my phone number. If anyone tries to put their personal info up, the Guides will remove it.
The point of the map is for other members to see what places there are a lot of members in. (If anyone gets any stalking PMs, they'll report it to a Guide anyway.) It's not dangerous.