In case of full scale nuclear war, do you think that people will be using their remaining energy sources to run some bitcoin nodes? Even in space? That doesn't make much sense.
Value of bitcoin is based on demand and supply, so what do you think demand will be when most of humanity has died? And it would definitely die. It's not like Elon would take us in space. If he was considered about helping other humans he would already use his wealth to do something about it. But it seems like opposite is happening, and cutting help was more in his wheelhouse.
Handful of remaining people in space would have more acute problems then how to trade.
If most of humanity has died, Bitcoin (or money) won't be that important to the remaining survivors. I mean, what use will it have? The only ones that will make use of Bitcoin would be robots and AI.
Either way, running Bitcoin nodes in space isn't a far-fetched idea. It's a "fail-safe" in case things go wrong on Earth. More like insurance against natural disasters (acts of God) or totalitarian states. I believe it's going to take decades, if not centuries, before crypto reaches its end. Assuming there's no calamity before then. Who knows what surprises lie ahead?
We do need to think that far ahead to see how the world is going. Talking about disasters or global wars, of course, I think everyone would be saving themselves, and they wouldn't know where they were at that time or what the situation would be. Talking about a future full of chaos is a normal mindset for some people, trying to find a way to survive in the future, using today as a form of anticipation. I think people will prioritize life over assets, like Bitcoin or something else.
I wonder how Elon got to Mars? If he could, he would have done it today, but what happened? He's still experimenting, and it's not guaranteed to succeed. We can also think of space expeditions as just hopes and dreams that won't happen, and we'll just be walking on Earth. Especially when it comes to running a node, who will carry it? Will it be that important in times of chaos?