That's so Morrissey.
It's great if the vegans you knew had adequate B12 levels. Like I said though, they'd have to be taking some sort of supplement or eating a fortified food as B12 can only be found in animal products.
That study did not claim vegetarian diets led those people to have greater heath issues. It stated that those in the study who self-identify as vegetarian had greater health issues. Why? Which came first, poor health led them to become vegetarians? Or diet caused the health problems? It seems to be the former. Those with allergies tried a veg diet to combat them. Those who oppose vaccines also oppose eating meat. Seems it is a case for the veggie lifestyle/mindset being the correlation here and not the diet itself.