Judging by the downvotes, there are a lot of surveillance state apologists/quislings in here! Oops, I mean "founders".
It's also not uncommon for police officers to use their tools to stalk women.
Now we're given the same untrustworthy officers full profiles of an individuals travel history without a "need to know". If you can't see how that's dangerous, I don't know what to tell you. In the US if someone is threatening your life, you can typically shoot them if you're out of options. You usually can't do that with an officer, even if they're off duty. The rest of the cops will stand behind that thin blue line and harass you.
And Flock specifically has already been used for this multiple times.
When nazis kill jews that is bad.
When jews kill nazis that is good (arguably (it used to be obvious but now it is only arguable)).
Symmetric situations are not equivalent.
This video here literally catches a K-9 officer faking a drug hit just to harass this guy over an expired inspection sticker. https://www.youtube.com/watch?v=Cv5kXxiJiMA