Did he do it? Nope... I think he is just blowing steam off. And I've owned dogs for my whole life, and I've never yet seen one where running straight at you growling was a sign of submission. Growling on its own can be, but not growling with teeth bared while running at you. Also, showing submission does not mean they were sweet dogs. Waaaaaay too many dogs are taught to submit like that out of fear (especially of something they recognize as a weapon, i.e. a gun), not out of proper training and a desire to please. Also, do you know for a fact (since you say/strongly suggest it several times in the first post) that both of the people involved had no experience with dogs at all, and had no clue how to interpret their body language? Maybe she put on her gun BECAUSE she knew she might run into these pitbulls... it sounds like they have been running amok for some time. If these dogs have been running free in the neighborhood harassing people and other animals, and there is no HS in the area to take care of them, I wouldn't personally blame the guy too much for having the urge to stop the problem by killing the dogs, though I don't think that is really the best solution.
If we want people to take us seriously about what sweet little lovers bully breeds can be and how wrong bans are, I don't think we can effectively do so by pretending that there aren't pits and amstaffs and the like that have been abused and brainwashed into being deadly to humans. Ignoring/denying the real problem (bully breed abusers) only fuels the fears and paranoia of the 'other side'. Not all pits are sweet babies, and they have an enormous physical ability to do harm. Fighting the prejudice doesn't mean pretending to be ignorant of the truth. Mocking and undermining people who have had negative experiences with pits feeds in to the bans. You can't change someone's mind by undermining their fears.
Do you know the cirsumstances under which the third dog was shot?