I'm not sure what being a 'saint' - or not being a 'saint'! - has to do with it?
You can like a drink yourself, but still see the benefit of certain alcohol-free or alcohol-limited environments.
It's perfectly possible that Walt liked a tipple, but that it still wasn't what he wanted for his family theme park.
If as Brian says above, Walt avoided smoking around kids so as not to set a bad example, then it makes sense to me that he might not like how Epcot has evolved in terms of alcohol for similar reasons.