Question: Is it safe/right to deploy spinnaker to same kubernetes cluster which spinnaker will manage?
Answer: Yes the architectures of Spinnaker and Kubernetes compliment each other very well, and running Spinnaker in the same K8s cluster it is managing is definitely safe,

In this document is Specifically states the following
https://www.spinnaker.io/guides/tutorials/codelabs/kubernetes-v2-source-to-prod/