Many things...many.
Well first off, I'm currently getting the same thing from my grandparents. Very old fashoned people, go to the gym every day, eat well, they never drink or use any type of intoxicants aside from caffeine. I figure they would be happy with me for kicking a eight year habit that has been slowly killing me. He is a bit happy, but he tells me that I'm still getting a drug into my body. And? Coffee has drugs, and if you think about it, drug is a term we have created for a chemical that alters our mind or body in some way. Though words have meanings, they are a human creation, so semantics can be put in place. Don't vitamins and other dietary chemicals alter the body mind? In a sense, everything is a "drug". So why single out nicotine. Because it is so associated with smoking, just as coffee is associated with caffeine. Just because it's recreational as opposed to dietary doesn't make it so different. Imitrex is a successful migraine medication. It is also derived from psylosyban (sp?) which is the psychoactive ingredient in hallucinogenic mushrooms. But one is ok and the other is not? Same drug, so why is it ok to use it when in need as opposed to when you want to have a good time?
Also, does he use caffeine? Both caffeine and nicotine is derived from plants as a natural incecticide; They are very similar. As him to quit drinking coffee or soda, observe his reaction, and compare the two. Why is drinking a "poison" better than inhaling a "poison" when cumbustion isn't involved? Also he is a cop, whicb makes his potential for dying a lot higher than yours is from vaping. Alcohol, pharmaceuticals, the list goes on, but does not include anything less dangerous than a bit of nicotine.
Lastly, be strong, and take pride in what you are doing. Stand up for yourself. You've accomplished something that many people cannot, do not, and eventually die from the lack of said accomplishment. Tell him if you want to buy it and use it, you have every right to, especially if it is essentially harmless to you and the people around you. This is the only life you get, so do what you want. Want to indulge in and unhealthy habit, go for it. Want to become more healthy, go for it. Want to combine the best of both, even better. And don't let anyone take that from you.
Ugh, why are my posts always so long...and I did this from a BlackBerry Storm. Annoying.