Note that this rewrite has a lot of resources at its disposal. The porting.md file has a ton of direction, more than historically an LLM can keep track of: https://github.com/oven-sh/bun/blob/46d3bc29f270fa881dd5730ef1549e88407701a5/docs/PORTING.md
But Anthropic acquired Bun, so I imagine this project has effectively as many tokens to use as it wants.
If this rewrite succeeds, this will effectively not only be a "fuck you Zig for not accepting my AIgen patches", it'll be a big headline and marketing story for Anthropic: look! Claude could rewrite Bun from Zig to Rust!
It's hard for me to read this then as anything but an experiment to see if Anthropic can get a big marketing boost in favor of vibecoding from.