I think that might be an overreaction. I generally agree that any dog who bites a person without provocation should be put down. However, in this case: (1) they were in a place where people agree not to use leashes and (2) he didn't let go of his dog's collar when the other dog charged. I would humbly suggest this was a mistake on the part of the original poster and I wouldn't necessarily blame the dog for it.

Dogs go for each other's throats. If you've ever seen a large dog grab another one around the neck and do the "shake of death," you quickly learn not to get your hands involved in that. Most of us who keep large dogs learn how to manage this kind of situation without getting bitten. I'm sure this sounds barbaric but dogs will be dogs. They will bite each other and if you put your hands in there, you're guaranteed to get bitten too. This applies even to good, trained dogs; even the best of them can be unpredictable and it's the responsibility of the owner to learn how to manage it, which is why I think pteron asked this question in the first place. I think it's great that he wants to figure out how to deal with this, without saying the dog should be put down, etc.

My $.02.