“Removing the imposition of beliefs is not in itself imposing beliefs.”
You’re in denial that you are imposing your belief system. You are imposing your belief system on an entire society, by forcing society to deal with the results of an activity you, contrary to facts, believe to be not harmful.
That’s really not libertarian at all, it’s creeping anarchy.
The question isn't whether it's harmful. Lots of currently legal things are harmful. The question is whether you think you have the power to tell a supposedly free person what he can or cannot put into his body. Telling him that he cannot is imposing your beliefs onto that person. You might as well be telling him what religion he can or cannot believe.