I'm all for gun control, but this does seem like just a couple of accidents. I think if we stick to the larger issues around guns there's already a strong enough case for gun control and we don't need examples like this which could easily disintegrate into finger pointing. ("You don't have a good argument. All your examples are just accidents." and so on.)
That said, I'd never go to a gun show myself. As a pro-gun control liberal I feel like I'd be as safe as a black person walking into a KKK rally.