Huh... You know what I see?
I see an ex-smoker who quit cold turkey who is frustrated because he KNOWS he wants to try an e-cigarette. He's probably very frustrated because he feels like he wants to start smoking again - shoot, I have quit in the past and started back again. A friend of mine quit for 18 years and ended up smoking again!
His pride won't let him start a new habit because now he's on the "ANYTHING NICOTINE RELATED IS EVIL" pile of soapboxes and if he quit cold turkey everyone else should too! Why should anyone have any fun while he is miserable? He doesn't want to be judged!
That's what I see... Jealousy, envy, frustration.
Tell him you'll give him a PV that he can sneak in the bathroom. No one will know

You wont judge.
I might be totally off base with this, but this is what I've found to be the case with most ex-smokers. I'm just waiting for my brother to chime in about my vaping. We're not speaking at the moment though. Regardless, my brother quit smoking cold turkey but he enjoys other burning leaves... If you catch the whiff... err drift.