I wouldn't be surprised, though I would be similarly skeptical that other healing-related issues would sway people one way or the other either since (at least the vegans I know) don't adopt the lifestyle for health reasons.
Very large effects are unlikely given the number of long-term vegans who seem to maintain sufficient health. Whereas small effects might be considered a worthwhile sacrifice.
Agreed as a vegetarian, this study being called damning is a joke. Veganism has a pretty good track record with respect to health outcomes. Committed vegans that I know would still do it if it lowered their lifespan, because they are doing it for a higher cause (environmental, moral, spiritual, etc.)
Very large effects are unlikely given the number of long-term vegans who seem to maintain sufficient health. Whereas small effects might be considered a worthwhile sacrifice.