There could be a lot of reasons for his reaction, none of which are an excuse by any means. It's possible that he was never taught to deal with emotions properly. Perhaps his parents raised him to bottle his emotions and that showing vulnerability is bad. That doesn't necessarily mean he's a bad person; he's just not accustomed to dealing with his feelings, let alone someone else's.

It's also possible that he was distraught over something and didn't feel he could control his reactions while in such a state, thus chose to take a step back and calm down before responding.

It's also possible that he's an arse.

I'd say give it some time and talk to him about it calmly and rationally.