If doing something you feel is wrong is hypocrisy, then the charge becomes meaningless. We're all guilty of that. If Rush made excuses for his habit, then I would also call him a hypocrite. If he tried to explain that his actions were not so bad, or that it was OK in his case to abuse pain meds, but not for others, then I would call him a hypocrite. If he resisted arrest, or whined about drug laws being too restrictive, or too harsh, I would call him a hypocrite.
Besides that, I've listened to Rush for more than a decade, and I don't recall him railing against drug addicts. I'm sure he's done it from time to time, but some appear to believe that drugs are his only topic.