That poor man was exposed to an awful lot of it.
I'm always super cautious with weedkiller - cover up, spray it then back in the house, strip, clothes in machine and me in the shower. I also only use it rarely for things it would be very difficult to get rid of otherwise. But even people who use it less carefully in their garden are unlikely to get anywhere near as much exposure as the man in this case, and a huge amount of things are potentially carcinogenic if you're exposed to enough of them.
Just saying we don't all need to panic.