> Management eagerly approved the Rust rewrite option because it was a great marketing opportunity to showcase their new Fable model, Anthropic already uses Rust, and Zig is openly against using Anthropic’s products.

Yeah, don't discount how powerful "marketing" is to management/executives, and also don't discount how absolutely ridiculously petty people can be, especially people who end up like CEOs and similar, requires a particular person. I can definitively see reason #1 and #3 from that to basically already set in stone that Bun had to be rewritten in Rust.