The Kubernetes component manifests must be owned by root.
The Kubernetes manifests are those files that contain the arguments and settings for the Control Plane services. These services are etcd, the api server, controller, proxy, and scheduler. If these files can be changed, the scheduler will be implementing the changes immediately. Many of the security settings within the document are implemented through these manifests.
How this relates to the STIG checklist: STIG vs SCAP benchmark.