FT, here is the problem with just quoting a stats like you did in the title:
We don't know what else the 2 groups do right and wrong health-wise speaking in their lives. It is probably safe to say that vegetarians care more about their health and they exercise more and do unhealthy activities less.
So the bottom line is this: It is entirely possible that it is not just the eating habits that gives them longer lives but other factors. Maybe if we do a strict study where they do everything the same (drinking, exercising.etc) except meat eating, their advantage comes down to nothing or very little, let's say 2-3 months....
Not to mention it is possible that meat eaters enjoy life better. As an extra point, in this over populated world, do we really want everyone to live as long as they can?
As I always said, do everything in life with moderation, and you will be fine. Also, there is the issue of free choice/will, if one wants to indulge in a bacon fest, let him....