This article (likely the one you found) is only about a year old. You're absolutely right though. The HAT treatment is only available to addicts who do not respond to other treatments. This tracks with everything I've ever heard about the program. People post about free heroin for addicts, but it is not that simple at all.

The only other thing I've heard, that I didn't see in this article, is that the dosage provided is typically not enough to get high, but enough to resolve the withdrawal symptoms. Maybe I'm wrong about that, though.