Whilst I always like to support fellow STWers, I can’t help thinking your thread title relates to you. I know his reaction was extreme, but he was provoked a bit.
When executing a manoeuvre it is your responsibility not to block the road for other users, no matter what mode of transport they happen to be in/on. Whatever you do, you should not make other road users brake to avoid you.
I am afraid I am with the cyclist on this one. You blocked him and have been a bit arrogant in expecting him to wait. Sorry. What would it have taken out of your day to simply wait for a more vulnerable road user to pass safely and unburdened by your ill-placed u-turn?
As a cyclist I would like to think I am extremely sensitive of the vulnerability of fellow cyclists when I am in control of a car or motorbike. I think we owe it to each other.