I had an actual look at the code, and because it's a translation it's not just straight up de novo slop. The bits I saw were fairly straightforward 1:1 translations, so the Bun developers should still be familiar with the overall structure and logic.

I still think it's mad, but not quite as mad as you might first think from the headlines.

I agree but would propose the weaker argument: no set of human contributors have, put together, read and understood all the code. Even in artisanal-coded projects of sufficient size, it's rare that any one human has read and understood all of it.