I'm not seeing that death date. And history shows that even traditional news outlets can be badly wrong in the immediate aftermath of a shooting. James Brady didn't die in 1981 - https://en.wikipedia.org/wiki/James_Brady#Shooting - even with "all major media outlets" (per Wikipedia) saying that he did.
Watching the video of his shooting may change your perspective. I don't advise you do, though I'll absolutely confirm it would be miraculous to come back from something like what the video shows.
It was an absolutely brutal video to watch. I agree. Even with the absolute best field first aid, EMS and surgical response, arterial bleeding I think has a 60% survival rate? Again, if everything goes perfectly, timed perfectly etc.
TIL there's a term for this! I've always been quite troubled by this propensity some people have to be the first to report the death of someone famous.