Love Go, but here's a good reason: This would make a cool piece of software for inclusion on the base system. Go produces relatively large binaries (for good reasons of course) and therefore it would probably be harder to ship.

Meanwhile, C++ runtime almost definitely is going to exist on most bootstrapping images, so it's a lot easier to justify its inclusion - the cost of the C++ is greatly amortized.

It could easily be written for any Bourne-compatible shell. A compiled language is overkill, and C++ is a security risk.