He's not a prime example of anything to do with fruit making things worse. His chosen therapy just as likely had no worsening impact on his cancer; the problem was it had no positive impact either and he put off surgery.

He had a rare form of pancreatic cancer that grows from the tip of the pancreas and can sometimes be snipped out without consequence early enough that it doesn't spread.

He presumably freaked out about it all nevertheless (because it's terrifying), avoided surgery for too long and ended up having a Whipple procedure, which is fucking brutal.

But there's still a pretty good chance he would have had early surgery and still ended up needing a Whipple procedure and still have passed away on roughly the same timescale. Because pancreatic cancer is a stealthy thing, and the Whipple procedure comes with its own frightening future.

It's really sad he freaked out, it's really sad he didn't listen. But it's not that unusual. He's far from unique in making irrational decisions in the face of terrifying diagnoses. Should it have been a slam dunk decision? Yeah. Of course. But there we are.