In case anyone is wondering if this signals a shift away from Go in container infrastructure, I don't think so. Docker, Kubernetes, Buildah and Podman are mostly Go code and I don't think there's much intent to change that.
I suspect the conclusion (that Go is not ideal for this kind of low level component) is accurate. OTOH, I wish it could be a memory-safe language instead of C. I can only assume there is some decent reason why Rust isn't used here, though personally I wouldn't know.
Another Rust option is Firecracker, it manages micro VM but can be used for Docker, ala Fargate and https://github.com/weaveworks/ignite