Joseph,
If damaging one’s body (which we have temporarily) warrants intervention, so much more so when damaging one’s neshama (which we have permanently) and olam haboh demands it.
True, but just as we wouldn’t stop someone from damaging his body by damaging his body (for example, were you to c’v find your neighbor’s kid using drugs, you wouldn’t shoot them), one must address the spiritual issue without causing further spiritual damage.