Facebook monitors and tracks the locations of users it deems a threat
Facebook monitors and tracks the locations of its users when the company’s security team finds that they are making credible threats on its social network.
The company actively monitors its platform for threatening comments. Once Facebook determines that a threat from a user is credible, the company uses data from its products to track that person’s location. However, it’s unclear what a ‘credible’ threat actually looks like.
Source: Facebook monitors and tracks the locations of users it deems a threat – The Verge