After reading the long Github thread, I think you're right. It's probably just as simple as "what is the easiest way to copy our TS code 1:1 to a faster language". And this case Go wins due to its simplicity.

What's funny is that while I understood a chunk about why that made that decision, a ton of things they were talking about went over my head. But then we they showed the side-by-side, I was like "Well that makes sense".