No need to debunk the report -- most medical claims are based on correlation studies, which are important, but hardly definitive. There are far too many variables in diet make such simple statements. What matters is how the individual does on his or her diet.
That said, many people do quite well on vegan diets. President Bill Clinton has gotten quite healthy again after his heart problems on a vegan diet. However, individuals have differing responses to diets, and they also change during life.
The "problem with vegans" is that so many of them are hardcore evangelists, but it also happens with people on Paleo, Low-Card, and other radical diets. It's not the diet, it's the dieter.