Can you show me some examples of abhorrent behavior? In the few reddit threads I skimmed about the bombing everyone was surprisingly mature, especially when pointing out 'suspicious' people.
Not in my opinion. They were just people trying to catch the bombers. No one was jumping to conclusions from what I saw (maybe some did but they were downvoted further down than I scrolled), rather they were just pointing out scenes that looked suspicious to them so that the police could investigate further. While there have definitely been cases in the past where a line has been crossed, I don't believe that to have happened this time.