Healthcare should not be tied to employment (see: corporate-employment-as-citizenship), and the general health of the population is (tautologically) a public health concern that needs to be addressed from the top, not the bottom.

Trying to "fix" people's addictive behaviors by denying them employment is like trying to cure the common cold by wrapping the patient's head in duct tape so they can't sniffle and cough anymore. Poverty and stress are uncontroversially regarded as risk factors for addiction, and in America if you don't have a job and you aren't a multi-millionaire then poverty and stress are what you will get.

Oh, and no, I'm not a smoker. I do drink a lot, which is something that's arguably just as bad or worse than smoking and yet nobody seems to give a fuck about it. Why is that?