Few things are more Microsofty than a team reaching over to a competitor's language instead of using their own and to boot none of the reasons given so far seem credible, good job to the team nonetheless.
I think it's a mature decision, besides, Go is an open source project, calling it "a competitor's language" is a bit derisive. The developers behind Go, Typescript, C#, etc were designing languages well before they were hired by those companies, I don't think they consider their languages a "google" or "microsoft" specific language per se.
Totally agree about reasons, they have some hidden agenda behind this decision that they don't want to disclose. Rewriting in native code allows step-by-step rewrite using JS runtime with native extensions, but moving to a different VM mandates big rewrite.
My most plausible guess would be that compiler writers don't want to dig into native code and performance, writing a TS to Go translator looks like a more familiar task for them. Lack of JS version performance analysis anywhere in the announcements kinda confirms this.
