Thanks for the response, you make some very points. Sorry, I had missed your response on the original post. I don't know if it was there yet, or because for some reason their blog is configured to only show the first two comments by default. :/ Either way, my bad.
I think my bias as someone who spends too much time looking at social science papers is that the protocol allows for spillover effects that, to me, imply that the results must be interpreted much more cautiously than a lot of people are doing. (And then on top of that I'm trying to be hyper-cautious and skeptical when I see a paper whose conclusions align with my biases on this topic.)
Granted, that sort of thing is my complaint about basically every study on developer productivity when using LLMs that I've seen so far. So I appreciate how difficult this is to study in practice.