It's a "a lot of things" thing. Generally, the taboo around such behavior is just a symptom of a lack of empathy.

Just about any person could go into a panic while in a state of stress and do something irrational, and just about everyone does at least a few times. In a shared moment of stress, you might see more empathy because "any of us could have panicked/froze/etc.," but if it's just you, "something's wrong with that person."