Sometimes I feel like Dustin Hoffman in Marathon Man where Laurence Olivier who plays the demented Nazi dentist keeps asking him “is it safe?”
Tobacco harm reduction, and harm reduction in general operates on the principle of whether an action or substance is safer than another, not so much their absolute safety. One of the most prominent anti-tobacco harm reduction strategies is to ask the question of “is it safe” in order to avoid the comparison (For example.). Other factors being equal, once you accept that nothing is absolutely safe but that some things are safer than others, only a moron would not see the advantage in going with the safer activity.
Today, Michael Siegel had a good post on the FDA forging forward under their new tobacco mandate and pledging time and money to determine the toxic elements in tobacco smoke. As he points out, we have plenty of evidence about it being pretty harmful and a better use of these resources, if health is the issue, would be to concentrate not on further determining how dangerous smoking is, but to finding and promoting safer alternatives.
On the other hand, we have anti-e-cigarette articles coming out daily on how e-smoking is or might not be absolutely safe. (See this BBC article.)
You could easily have made the same arguments against airbags and seatbelts. Those items, which have saved the lives of thousands to date, have on occasion caused death when otherwise it might not have happened. They are not absolutely safe. But they are safer, and that is why they are now standard equipment in automobiles.