During periods of low demand we can shut down coal plans (instead they spin up new ones to mine). And even solar is not without guilt as equipment goes end of life.

Even if we were to live in a world powered entirely by even production base load such as nuclear we'll still have hydro that can be saved, and even pump storage hydro if there's still left over.

There's no getting around it: this argument is still spinning destruction to be construction. And it's clearly a spin that's being done for very direct financial gain.

But remember too that when you say "low demand", what you mean is that it sets a price floor on energy. The equilibrium for miners is to continue mining always when the price is lower than their ROI. This means that fluctuations in a cryptocurrency can mean that demand is unmet, if such demand is not able or willing to pay the same as this rentseeking mining is.

Concretely: If we were at equilibrium, and we suddenly invent an energy source that would drop energy price by 10x, real prices would still not go down, because economic incentives such that mining would eat up ALL of that potential lowering of price, and we'd be back to the price we started at. All price of energy would be bounded at the lower end by cryptocurrency mining incentives.

We'd have rolling blackouts when the currency goes up. Or when gas fees/attestation fees go up, depending on the details.

We'd have doubling-to-quadrupling of energy prices like we've had this winter, except triggered by even more causes.

So no, I'd say it's the same as what I've said, or worse.