Clemenza was overweight -- and besides, does everyone in the mafia need to be whacked? Doesn't anyone die of natural causes?

I know that Frankie Five Angels thought otherwise, but couldn't it have just been his anger at the Rosatto Bros. that was clouding his better judgement? Plus, other than Frankie's line about it "not being a heart attack", Clemenza's death is not mentioned again. If we were supposed to believe it was something else -- wouldn't FFC and Puzo have planted something to confirm our suspicions?

Now, if I were Winegardner, I would have explored the possibility of Clemenza getting knocked off instead of him collapsing on a stove (which I guess was supposed to be some kind of attempt at black comedy fused with irony) but in the films, I like to think that Clemenza was a loyal guy who was able to stay ahead of getting killed my rival mobsters and dying on his own terms, even if it was just a heart attack.

What does everyone else think?