Whilst I agree with you in that I don't think this is an optimal approach, at the same time I'm curious as to whether this would create a significant black market for cigarettes.
Anybody already addicted will continue to have access. Anyone not addicted has to overcome the barrier of acquiring it illicitly, which works in tandem with education about the harm it does.
Considering how bulky cigarettes are compared to most other drugs, I wonder whether most dealers would carry around loads of cigarettes - particularly if they'd be at risk of being prosecuted for having them (which I don't think is the case here, though).
However, it would probably increase the rate at which weed is cut with tobacco as it increases the addictiveness and ensures customer dependency for the dealers.