A drug user or a non-drug user who is judgmental about some other person's drug of choice is usually not judging the narrow aspect of the drug taken, but rather the real or imagined effects of the drug on a person's life and the lives around the drug user.
A right of a person to take a drug or not take a drug can't depend on if anyone has ever become an asshole on a particular drug. An individuals personal history with a given drug is more important.
OP or anyone can decide to associate or disengage from anyone for any reason. The decision to take drugs is not a decision to accept every drug or every drug taker, but if one is asking not to be judged by their drugs taken but by their individual behavior, extending that courtesy to others seems fair and logical.
As far as hypocrisy, no one is 100% consistent regarding their values- especially while living an active life in the real world. The most any of us can do is to make an attempt at being fair within the social matrix we find ourselves. I make short cut judgments about people because of brand preferences, profession, their politics, music , favorite books and movies, etc. It makes sense that people's drug use or non-drug use plays into the thumb-nail profiles we all end up making about other people.Short answer it is not hypocrisy to make differential determinations about people by the drugs they use, but the drugs people are using are not any sort of super reliable benchmark in my experience. Taking each person and their whole life situation in to consideration is the way to go in my opinion, when we have the time to do so anyways.