I'm not sure why some people react in that way when they are unfollowed. But why were they being followed in the first place? I know some companies like to follow every single person they can with the expectation they get followed back and then boost their subscriber numbers, and I think it's a silly game to play.
I once got followed by a new local radio station that was launching in my area (I work in radio and they seemed to be following every radio person in the region). I thought, fair enough, and followed them back.
A few weeks later, after they'd started up and the dust had settled, I had a look at their Twitter page. "Following: 0." The cheeky gits had followed everyone, got a bunch of followers in return, and then deleted us all! That was enough to lose them a significant amount of goodwill from me and I promptly unfollowed them.
