It was a mix of who came up with it, and having hit jackpot with Docker and Kubernetes rewrites from Python and Java respectively, into Go.

Had the rewrites not taken place, or Rust already being 1.0 by then, most likely would have had as many commercial success as Oberon and Limbo managed to.

You see this happening nowadays newer CNCF projects tend to be done in Rust, and there are even some that even go the C++ way, e.g. Envoy.