What is more important? A kid's life, or the honor code? Obviously the kid's life is more important right?
The threat of getting kicked out of school/kicked off the team/losing their scholarship/being a huge disappointment to their parents is obviously a huge problem for them. Many people with substance abuse problems will look for any reason not to get help. These are obviously HUGE reasons. When a kid is already down this path, they should have reasons and encouragement to turn their life around. The current policy forces them to hide it and that is dangerous IMO. I imagine that the vast majority of kids that gets kicked out because of substance abuse weren't self reporters.
Many times hitting rock bottom is what people need to turn their lives around. Many times getting kicked out of school would be the wake up call that some people need. But this isn't the point. The point is that they have the opportunity to do it on their terms and not have reasons to hide it.