Strange in what way? Mitchell has also stated that he reviews every line of code that goes into Ghostty so I don't think its quite the same as the Bun rewrite.
At work I use Claude, but it is a considerably larger and quite complex codebase. I use LLMs a lot, but it is a common weekly occurrence for me to correct misconceptions, bugs, or overengineering from Opus/Sonnet (Opus plans and reviews, Sonnet implements).