Wow. Poor guy.

The only thing i can think that it would be is that either it is the way the other one was bred or your intact male's hormones are sending one strong message of dominance.

I really don't know if there is anything you can do for the little guy.

Maybe:
If you can contact the owners see if it would be OK to buy some calming essences for the boy. [You can either apply them to the tummy or in their water (depending on the variety though) Lavender is the popular one.]