There's nothing rational at being triggered by neurotics or exceptions. Perhaps some can give reasons like "deep fear of the unknown" or rationalize their angry feelings by saying you or what is part of you is wrong because people are not that way (to their perception, of course), but I as someone who had troubles with depression, doubt that. With that, I'd rather not find any explanation to such behaviors. Why? Because that would lead to sympathy to such behaviors, which to my view are one of the leading causes of depression in society.

I also tend to think people lash at something which is different in an attempt to find an "anger trash bin" which would later become a depressed person.
Nothing to rationalize. It's all bad behaviors causing depression in the guise of rationality by saying "you're weird because of that zit, walk, voice, color, smiles". Those small neurotic reactions are the ignition of pain, and because such people are "unaware of it", they are never blamed. No wonder depressed people feel it's their fault most of the time. It's because of such primal behaviors as you described.