Your first line is a common misconception (though the rest is solid).
Solar and wind can switch themselves off very easily, so having too much is never a problem.
In fact, having "too much" is generally the cheapest option and something every sane grid is aiming for right now.
Once you actually have too much you can start to think of clever things to do with it, but again, that's the step after having "too much" because it's cheaper.
From an economics perspective, his first point is exactly correct.
Solar dumps tons of nearly free energy when it's sunny in summer, but produces much less in the winter, and even less on random bad weather days/weeks. ...and zero after dusk.
This has the impact of flooding the market periodically which makes financing the alternative power much more expensive.
In that environment, the plants you turn to for such rapid on/off production are burning fossil fuels.
You could also do nuclear, but there's no benefit to turning nuclear off, it actually obviates building any solar for day/summer/clearskies-only production.
This would all be obviated if batteries were cost-effective, but they aren't yet.
> In that environment, the plants you turn to for such rapid on/off production are burning fossil fuels.
This is the exact opposite of the truth.
The problem you're vaguely referencing, the so called duck curve, was a problem because fossil fuel plants can't ramp as fast as renewables.
One of the many existing solutions to this solved problem was in fact to ask the gas plants to ramp a bit faster, which they actually could do, they'd just never had to before. Still not as fast as renewables though.
The real reason we turn the fossil fuel plants off when we can and only turn them on when we really have to is because burning fossil fuels is expensive and polluting.
But luckily we can quickly minimize that, and save money, by building lots of renewables. And, as an added bonus, renewables and batteries ability to turn on and off so quickly provides many grid stability benefits that earn them money on top of the electricity they sell.
Solar and wind can switch themselves off very easily, so having too much is never a problem.
In fact, having "too much" is generally the cheapest option and something every sane grid is aiming for right now.
Once you actually have too much you can start to think of clever things to do with it, but again, that's the step after having "too much" because it's cheaper.