S.G.
My son used to get croup, if this is really croup it can be very serious. His throat would begin to close on him and we would have to take him to the hospital, they would give him a shot to relax his throat muscles so he could begin to breathe easier. The hoarse cough is not what I would call croup, it is usually combined with an inability to get enough air down the path way.
With that said, if someone cut off my air way I think I would be throwing a fit too, and I am a lot older than your son. He is probably scared and can not understand why he is unable to breathe as well as he should. He may very well be in pain. My son continued to have croup once or twice a year until he was about 10 years old. he said that it would hurt when he tried to breathe and it was scary when he could not get enough air.
Dont just assume it is all about temper, the poor kid maybe very scared.