I do think the reaction to this Bun Rust rewrite - from both sides of the table - is massively out of proportion. I think it's got something to do with the size of the diff, but enormous diffs by traditional auto-generated tools are not uncommon either. Try running `cargo fmt` on a large codebase.
If you look at the code, it's a deliberately conservative rewrite. Virtually every type, function, branch, etc. is preserved. I'd argue that it's the sort of task the author would have solved faster and easier by just serializing the output of a Zig parser into Rust: it's not especially different to the sort of output c2rust produces, for example.
Put simply: it's not a shocking display of the efficacy of LLMs, it's actually quite a constrained and well-scoped task, repeated many times. It's 500 undergrads in a trenchcoat.
And so, I'm unconvinced that it should really change anybody's minds about what these tools can do, because it's nothing we've not seen before.