I know he's said he's gotten into a few scuffles in the past, but I don't think he's ever admitted to a major confrontation. I think it helps that he's an old man now.
I love street photography and I love his photos but can't really condone most of his tactics. I don't want to get into a "photographers rights" argument, most of us know what we can and can't legally do, but I find his seeming total disrespect for his subjects kind of grating... maybe it's because of the photographic work environment he worked in, "get the image at all costs"... I don't know.
There's a fine line between exercising your rights and pushing them in peoples faces. I think it's photographers like Bruce that are giving street photography a bad rap. Yes, photographing someone in public is legal, but at what point does ambushing someone with a camera and popping off a flash inches from their face start treading on other laws like "disturbing the peace"... wiki describes it as:
"Disturbing the peace is a crime generally defined as the unsettling of proper order in a public space through one's actions. This can include creating loud noise by fighting or challenging to fight, disturbing others by loud and unreasonable noise (including loud music), or using offensive words or insults likely to incite violence."
I would consider a close quarter camera and flash ambush as falling under that definition... if loud music counts, why not a bright light?