YOU'RE ASKING A DIFFERENT QUESTION!
Difficult to say, that's a different scenario entirely.
Reporting it is the only option that would have a decent chance of stopping it. That for me is a no-brainer.
If you then report it, numerous things can happen if you reveal you reported it so it's an individual call based upon your interpretation of what would occur. If guy/woman was a psycho roider and you felt they may assult you if you revealed you reported them... you'd be silly to do so.