Well put. -- By saying that States have a 'right' to criminalize private non-harmful sexual behaviors, -- we in effect are saying that States have a 'right' to criminalize private non harmful behaviors regarding the carrying of arms, for instance.
If I may inflict this on you here is a rather long post which has some relevance to this idea of prohibiting one behavior to get at another:
Are you saying then, -- that States have a 'right' to criminalize private non harmful behaviors regarding the carrying of arms, - for instance?
However it is probably constitutional to try to get at drug use by prohibiting drug possession in the absence of a specific constitutional right. That is not to say that I think it is wise.