Better to find a group of dogs (without puppies) who he knows and likes to play with. If these people are all friends maybe they can work something out.
But to say it only happens occasionally and there can be bites or blood involved, is rather like saying my kid can sorta drive but occasionally there is an accident on sometimes there is blood and injuries. So do you keep giving the kid the keys to the car? Nope.
His respect for his person needs work, and she needs to find a good trainer to help her.
Is is very real that some dogs don't like puppies and never will. You probably don't like everyone you meet. Hopefully you are still polite to them. This dog needs to learn that he doesn't have to like everyone but he does need to have good manners.
One of the very real problems with this situation is that he is being allowed to bully puppies and not only can he really hurt one but he is also setting them on the road to fear and possible future aggression down the road. It becomes a terrible cycle which can be stopped with good training, management and being a responsible dog person.
+1 BIG TIME
This dog should immediately stop going to this dog run, imo, your friend is rolling the dice in a silly way I'm afraid. It seems highly likely that one day his dog will seriously harm another dog....which in some states/provinces means the offending dog will be put to death. simple as that.
If this were my dog I would try to group obedience train it with other dogs from a referred dog trainer with experience with aggression from someone you trust. The referred part is the most important part of this sentence
and if this did not work, my dog would never see that dog run again.
Play dates with larger dogs as per tenderfoot's suggestion is an awesome idea in the short term.