Attacking Goldwater for being a warmonger is one of the most hilariously hypocritical arguments ever, given who the alternative was in the 1964 election.
It’s certainly ironic in hindsight, but didn’t seem to be so much during the campaign itself. Certainly LBJ doesn’t sweep every damn county in places like upstate New York and Vermont if he hadn’t managed to convince a ton of moderate Republicans that a Goldwater presidency would be the literal end of the world. Say what you will about the ethics or honesty of that, but it certainly was extremely effective. And Goldwater didn’t help himself by sticking his foot in his mouth at every turn and talking about using nukes in Vietnam himself. And whether he actually would have done that or not, LBJ didn’t regardless of everything he did do.