Could a hotsauce maker make a hot sauce so hot that he himself could not drink it?

Yes. Yes he could.

Darwin award right there.

Motherfucker died from eating a tomato-based hot sauce? The itching mentioned in the story suggests to me that it was some kind of fatal allergy, but if it was actually in line with the (stupid-ass) theory that it was a heart attack brought on by the spiciness, that is some shame for the ages right there.

Pretty clearly he died from an allergic reaction to something, not the level of hotness of the sauce.