He said he didn’t like grumblers and it was time for revenge:

An employer for a German company fired three of its ten workers, who he claimed were “disturbing the peace” by demanding a smoke-free environment.
The protests of the three employees were in response to the regulation that although citizens have been prohibited from smoking in pubs and restaurants, they were still allowed to light up in small offices.
[…]
“Smokers have always been our best employees. Non-smokers interfere with corporate peace,” Jensen was quoted by MSNBC. “Our non-smoking employees were actually convinced that they had the right to smoke-free zones. They just complained all the time about smoking, and I don’t like grumbles.”

I don’t know, I’m all for freedom of the employer to hire who he wants and to have the working conditions he wants (as long as he doesn’t discriminate or create an unsafe environment) but it can be really annoying trying to work while you’re breathing in smoke. If you have sinus problems, it can be pretty painful.
(via)