And the "collective cost" argument is silly, because it can be applied to any personal liberty that negatively affects health.
http://www.forbes.com/sites/danielfisher/2013/12/12/study-fi...
www.youtube.com/watch?v=3s8yqj3EL7A
1) From your link, "The study doesn’t cover the many other ill effects of breathing somebody else’s cigarette smoke, of course, which include asthma and possibly cardio-pulmonary disease." So not debunked exactly.
2) Penn & Teller are entertainers (and illusionists). They present controversial opinions for the sake of a TV show. It is not journalism and shouldn't be accepted at face value.
ETA: https://en.m.wikipedia.org/wiki/Penn_%26_Teller:_Bullshit!
Penn says, "right now, as I sit here, there probably is danger in secondhand smoke".
Asthma sufferers, for example, have all sorts of additional breathing difficulties when forced to breathe smoke (of any kind).
Heart disease is a bigger killer than cancer in many countries.
Plenty of non smokers also get cancer.
It would be different if smoking only affected the smoker, but as it affects the wider population (such as higher overall health care premiums), it deserves stricter controls.