Yeah, Flywheel was very much an early adopter of Go within Google and was written at a time when many teams were uncertain about whether to switch. Since then there've been a lot of commercial success stories both inside of Google and out (Docker, Kubernetes, Cloudflare, everything that Sawzall used to be used for inside Google, and a number of backend parts of YouTube), so using Go isn't nearly as controversial. It was quite a leap when the Flywheel work was done in 2011.