That is fine, but posting their picture is so wrong. She took their photo, while smiling at them. And then she captioned it: "Offenders" and put it on twitter.

This is the real issue here.

Let's for example go to your hackathon in Vegas. Lets say some asshole says something inappropriate to one of the high school girls in attendance. Do you really think that taking his photo, captioning it "pervert" and posting it to twitter is the right course of action?

I think you would find that most minority groups (whether they be religious groups, women in tech or geeks in high school) would be tired of asking those they consider to be offending them to stop.

Under no circumstances is that a justification for taking matters into your own hands. To suggest that it is creates a negative feedback loop where both sides feel justified to take ever increasing actions against the "aggressor" (from their perspective).

Well it's a good job that only a guy and his family's life were ruined, but thank goodness she didn't have to consider the implications of shaming the offenders by asking the two guys to stop violating her moral righteousness first.