Um, if you look closely, nowhere did I claim that the improvement in his health was due to him becoming a vegetarian. Adopting that diet was simply one of the life changes he decided to make, and his cardiologist had no problem with that choice. His cardiologist cautioned him that his diet at the time; one which consisted of a lot of red meat, would've hastened his demise. In that regard, his switching to a vegetarian diet did, in fact, improve his health.
You'll excuse me if I defer to the educated opinion of his cardiologist over the opinion of some yahoo on the interwebs.
He also quit smoking and started running and exercising more. I can state, without hesitation, that he's healthier now than when he had his heart attack, and he is healthier than just about any 30 year old I know...