Well, statistically speaking, vegans live longer, right? That does not necessarily imply that all the benefits come from the diet, and it certainly does not say

Well, statistically speaking, vegans live longer, right? That does not necessarily imply that all the benefits come from the diet, and it certainly does not say that going vegan is guaranteed to make you live longer, but it does mean that if you choose a random vegan they will be healthier than a random omnivore. So I think if you have to choose between the statements "vegans are healthy" or "vegans are unhealthy," there's not a lot of evidence to argue for the latter.