Why do cyclists hate letting buses out?

This is a question that I pondered when I was pulling out of a bus stop, after being flashed out by a car, and some toss bag cyclist attempted an overtake. He shouted out something that I didn't hang around to hear. He caught up with me when I was helping a wheelchair to get off and shouted something else. I took him over a few seconds later and I think I might have heard him say that he was going to report me!