Yes, lew, this "other person" did look up info on your family, including your daughter. I never even knew you had a daughter, prior to today.
However, you sent this person various vulgar messages/threats which drove them to do this. This person has also been threatened/harassed by you in the past, for no apparent reason. So today they just snapped and decided they were going to research everything they could on you, and then presented to you what they found. Can't say I blame them.
I did not see evidence that the person was going to do anything harmful to your daughter, or even any evidence that they were threatening to. They just let you know that they found her and had pictures of her, and also counter-threatened you with some of the info they found.
Given the circumstances which led up to this, along with your history doing this stuff to others on PFA, I couldn't blame this person one bit for how they reacted.