> There are precisely two languages that make the most sense to implement the TypeScript compiler in: Rust and TypeScript itself.
Incorrect. I can maybe agree that those are the only perfect languages to implement tsc in them (if there is such thing). But in the real world, "perfect" does not actually mean "it's a good idea". Go made the most sense to port to (especially before agents), more than Rust (although C# could also be a good idea IMO).
C#'s embeddability/interop story is even worse than Go's; IIUC this was the primary reason they chose not to use it.