A reason I have seen used effectively is "our daughter's friends and teachers get upset if we stink, and doubly so if we pass the stink to our daughter." Harmful or not, it is odious to many people including some vapers (not me) so especially in cold or burning-hot states, we still should not have to go outside. (In CA it is a difficult argument to make if you are north of Santa Barbara and significantly below Lake Tahoe in elevation.)
That could be used, but it's still a bit insulting to smokers? I guess if you are saying it to someone in person, rather than posting it online where smokers can read it, it's not so bad. There are plenty of other valid reasons why vapers shouldn't have to go outside or into smoking areas that don't rely on ANTZ lies: 1) it is a disincentive to switch to vaping if they still have to go outside or to a smoking area; 2) being around people smoking could tempt vapers to smoke (no fault of the smokers); 3) going outside/to smoking areas falsely leads the public to believe vaping is a danger to them; 4) going outside alone can put vapers at risk of crimes; 4) there is no scientific basis for requiring vapers to go outside (same is true of smokers, but that's not our fight); 5) businesses should have the right to decide if people can vape inside, not the government (especially with the lack of evidence there is any public health risk.)