I love the hand mouth habit more than I like the nicotine.
Exactly. I had to stop smoking about three and a half years ago before a double knee replacement. I tried an e-cigarette, but found it completely unsatisfying because the one I got didn't actually feel like a cigarette - too heavy and the balance was off. I fully intended to start smoking again when i returned home. However, because I couldn't smoke for several weeks, I realised how much I was saving, and decided to replace my car, and nearly saved enough in a couple of years to replace it. (I was a heavy smoker.)
Anyway, all that rambling is only to say that if I could find an e-cigarette that, for me, really mimicked smoking - weight, balance, same feeling when you drawback, etc, I'd have it in a flash. For me, nothing beat a cup of coffee after a meal, or a glass of wine, accompanied by a cigarette.
So anyway, my point is, your husband probably feels that he wants a smoke and is afraid he will succumb (and if he has one, he'll be back on them, probably smoking as many as he did before he stopped within a month - I've been there, done that). If vaping helps him not give in, so be it.