Thank you for writing this up—always good to see criticism of key ideas.

I want to contest point 4.

The fact that we can decompose “Good done / extra person or $” into three factors that can be roughly interpreted as Scale, Tractability and Neglectedness is not a problem, but a desirable property.

In ultimate instance, we want to evaluate marginal cost effectiveness ie “Good done / extra person or $”. However this is difficult, so we want to split it up in simpler terms.

The mathematical equation that decomposes the cost serves as a guarantee that by estimating all three factors we will not be leaving anything important behind.

Can you explain the bit about long-lived radionuclides?

How would they be produced? How would they affect “technological carrying capacity”?