I would argue that society should reserve the right to punish individuals who harm others for their personal benefit.
And I would argue that selling a physically addictive substance that directly causes harm with no benefit to the user for personal profit is causing harm.
So while I don't support arresting people for smoking, I 100% so support arresting people for selling.
There is no oxymoron.
Smoking is harming oneself.
Selling is harming another.
They are not equivalent.