I believe the argument is that it increases redundancy and resilience of the renewable power supply...
That redundancy is otherwise uneconomical to produce (if there isn't the demand).
When that redundancy is needed, that power can be redirected from the miners. Presumably the miners are expected to behave and switch off at such times, but there is no reason why that expectation can't be legislated.
One can easily structure an energy market to pay for redundancy. There is zero reason why we’d need crypto to fund expansion of renewable energy.
If freezing temps in Texas or Buffalo that lead to deaths don't encourage improving the grid, I don't think crypto will either.