I agree that the concept is really awkward and misses the point. In my personal views I hold that when you are talking with a person and something about them offends you, you shouldn't conflate the entire person with that one thing. As you mentioned alcoholism. You don't have to endorse or like that the person drinks to much or is dependent on alcohol. I think the wording of the Canadian supreme court is clumsy because I think its trying to tackle a different point entirely. A lot of activist groups have a tendency to use filler words in place of their aggressors. For instance people against drug abuse tend to claim that drug dealers and users are bad people. Now, we can see that individuals aren't necessary evil. A person who use or sell for a ton of different reasons. Quite a few groups who are anti this or that tend to use the phrase " hate the sin, not the sinner" in a multitude of different ways to claim they aren't against the people, but the sin. However, many of these groups go out of their way to effect the individual people themselves. So the phrase usually just comes off as camouflage.
As I said the wording comes off clumsy and misguided and can be abused due to its vagueness. These issues are very complex, and I think people are way to hasty to over simplify them, but that is the problem with all activism. Its trying to make complex issues easily digestible, even if it muddies up the entire issue.