The alternative to cold wars is hot wars. Do you really want another WWII (60 million dead)? The idea that peace will happen if we make shitty arms is historically untrue. The idea that peace happens when we make cutting-edge arms is historically true.
There is very little difference between arms and modern industrial chemicals. Without arms, we can still kill large populations by destroying their water supplies and crops. Even if you managed to rid the world of every weapon more advanced than a knife, if/when conflict arises, we can kill populations at a grander scale than ever before.
He is is making the correct assumption that even if some people want peace others will be more than happy to kill you and rationalise that it was actually a good thing. So you are both right: the alternative is peace or war. I would definitely prepare for war though. To do otherwise is naive and gratuitously stupid.
Si vis pacem, para bellum may be a practical advice, but the outcome of it is an arms race. Which is a big problem, because that feedback loop ties up resources and manpower that could be better used elsewhere. So even if it is the most practical option now (since we don't have a single global government), we need to recognize how shitty it is and maybe figure out how to reduce its impact.
But the nuclear game theorist's argument has always been that while functionally more dangerous (i.e. life on this planet could be obliterated at any moment), a nuclear-tipped détente has greater stability than any alternative (i.e. it is least likely to lead to hostilities).
I see the argument for nuclear de-foresting a lot like the argument against nuclear power. Yes, at face value it seems an obvious best option. However, when compared to the realistic alternatives, other approaches may be preferable.
It also allows both sides to maintain a minimal standing army while maximizing the cost of an opponent initiating hostilities. Most of the West's strategic nuclear position has historically been to counter an overwhelming Warsaw Pact numerical advantage in European conventional forces.
It's incredible how people pretend deterrence is for social benefit. It brought us already once near a global atomic war. Remember?
https://en.wikipedia.org/wiki/Cuban_Missile_Crisis
We would live in a better world without nuclear arms, that I'm 100% sure of.