I don't know, if you are interested read them. Their models definitely control for things like 'social class'. Furthermore I am not really convinced whether the small amount of extra socializing that alcohol brings has a significant effect on longevity (it might do, I am just not convinced).
My understanding is that the decent longitudinal studies fail to take account of the fact that a fair proportion of people who don't drink AT ALL are ex-alcoholics. But I haven't seen these studies in particular.
To be honest, in the UK, not drinking at all is a very strong signal for either being a Muslim or having some reasonably serious personal whackiness and non-conformism. Both of those seem likely to me to be at least as likely to explain health effects as the booze itself.
Dying or becoming severely physically/mentally ill is very likely going to significantly lower the output of your utility function, so it would probably be a very bad idea to ignore the low-hanging resources which can significantly extend the time for which you are alive and well. I have attempted to search LessWrong for a list of such resources, and haven't been able to find one.
Are there any books, websites, or posts that contain significantly low-hanging fruit in this area? If so, please list them in the comments below.