Incredibly inappropriate. You have 0 clue about anything regarding his medical history. Next time you want to attribute cause of death for someone from an anecdote, do everyone a favor and shut the fuck up.
Just via the Golden Rule, I would be happy if someone used my own bad example (I have the same condition that I attribute to Prof. Winston) to make the argument personal, if that motivated someone to pick up the apple instead. We lose too many years to high blood pressure, obesity, high glucose, neuropathy, etc., etc., to shut up about the donuts.
"I can testify that is downstream of too many donuts."
The above statement - specifically saying you TESTIFY - does not sound like speculation; it sounds like you are speaking as a matter of fact.
I fail to see what if anything, positive you thought would come from that post? You're in a thread where people are mostly positively remembering someone they respected and you essentially jumped in and said "yeah but the guy killed himself with his eating".... like you really think that's a good idea?
You might think you're doing some greater good - but there is a time and a place for everything - the message you're trying to send isn't going to land in this sort of environment, it's just going to piss people off and have you appear to be disrespectful.