I have heard this as well. For once I have to have some sympathy with the brewery. The artificial cigarettes are every realistic, and it could be difficult for managers and other customers to tell the difference from a distance.
The last thing a manager needs is for someone to light up on the basis that another customer is smoking a plastic cigarette, that's just problems for everyone.
And no I am not an anti-smoking fanatic, I smoke myself and hate the smoking ban.