GCE operates GKE which is a hosted Kubernetes as a service. I'm not saying that Google is using Kubernetes instead of Borg, but that doesn't mean they don't use Kubernetes at all.
So, people are using Kubernetes in the Docker community. Google offers a GCE service for that. This seems incidental to Go with community and demand really driving its use. That they avoid it internally where possible is still a strong point given the large ecosystem developing around Go. Assuming it's true that they avoid it for C++ and Java of course.
