Seems perfectly reasonable to me.
Perfectly reasonable for the man in the street MaizieD but not at all acceptable for a wannabe future Prime Minister. It is the PM's job to protect and defend the UK and its population by any and all means, including nuclear weapons if that becomes necessary. By admitting to any potential enemy that he would not be willing to use nuclear weapons, Clive Lewis has immediately played into their hands and given them the advantage. An enemy has to BELIEVE that a weapon will be used, if it is to be any kind of deterrent. If he was elected, Lewis has already made us the underdog in any future potential war, without setting foot into No 10! Hopefully the public will never put him or his like there again.