When it comes to college teams and drinking, I think we need to ask ourselves why underage drinking is not ok. Is it because it's against the law for those under 21, or is it because we have a moral problem with drinking, or is it because we are concerned that anyone under a certain age does not have the maturity or emotional stability to handle drinking? Or some combination of all of those?
For me, the latter of those three would be my main concern if I were involved with a college team. Yes, it's against the law for a 20-year-old to drink, but so is going 70 in a 65. My concern with it being against the law would be more of what the penalty would be, rather than the fact it's against the law. I view a 20-year-old drinking a beer about as seriously as I do a person driving 70 in a 65. I have no moral problem with drinking. So for me, that leaves the concern of the well-being of the person if she is drinking and isn't mature enough to drink responsibly.
So, you might ask, you're ok with a 14-year-old drinking if she can handle it? No, I'm not. I do think there is an age at which we need to assume that nobody is thought to be capable of drinking responsibly. For me, that age is 17. Or perhaps better yet, once someone is out of high school (graduated), then she should be able to drink as far as I'm concerned. I hope no one is alarmed by that, as age 18 was the law just 20 or so years ago.
The bottom line for me is that I would have rules in place for drinking for a college team more for strategic reasons and not for moral reasons. During the season, we obviously don't want our players getting drunk and having hangovers. We also don't want our players 21 and older getting the younger ones in trouble with the law for drinking. Out of season, I just can't see myself banning drinking for a 21 or 22-year-old. I agree a coach has every right to ban it to promote healthy bodies, just as a coach can mandate conditioning programs for the same reason. But just as I wouldn't ban pizza or candy bars, I wouldn't ban drinking out-of-season for those who can legally drink. I don't think it's realistic to expect them to follow the ban.