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While I suspect you can't start a fire from moonlight in practice, I don't think the arguments in this article are correct.

I guess if you're reading that as some kind of absolutely logical argument. I read stuff like that as an abstraction which just kinda works in the messy real world. Pretty much like how the typical explanation for how a wing works turns out to be an over-simplification. It only partly works that way. Actual wings are complicated, but in the aggregate, they just get enough air molecules to go downward to net out the forces to keep the plane from going downward. It turns out that there are a lot of mechanisms contributing to this all at once. (Which is something else he discusses in that series.)

It’s presented as an absolute logical argument of the form “you can’t use a lens to make anything hotter than the average surface of the moon.”

And it "kinda" works in the same way the simplified Bernoulli explanation of the wing works.

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