They probably think he's too young and immature, even though he thinks he isn't. If he is "worth his salt" he'll sort it out eventually. If not apparently it can emotionally scar them for life to the extent they wont try to mate with any hens, but if he is that much of a woss he is probably a bit of a write of anyway.
I expect it is the "head hen" who is sorting him out mainly - she's not having anyone usurping her rights - that is until he can stand up to her.
All the best
Sue
