At a guess it's because Boris literally wrote a book on TypeScript: https://www.oreilly.com/library/view/programming-typescript/...

I don’t doubt his expertise, I just am not convinced it’s the right tool.

To me it comes back to the premise I hear a lot from AI hype men (of which I do not subscribe but it’s worth clarifying that I find great value in using it for code) that the code doesn’t matter anymore. I just don’t know how to square that claim with the idea that we’re limited still by JS/TS being easier to use or approachable despite inferior TUI toolsets.