Question: How to setup Spinnaker  with restricted namespace access?

Answer:You can try to get your admin to give you access to a ClusterRole+RoleBinding that has access to namespaces read.

Something like this:

kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: namespace-reader
rules:
- apiGroups: [""]
  resources: ["namespaces"]
  verbs: ["get", "watch", "list"]

---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: read-all-namespaces
subjects:
- kind: User
  name: your-user
  apiGroup: rbac.authorization.k8s.io
roleRef:
  kind: ClusterRole
  name: namespace-reader
  apiGroup: rbac.authorization.k8s.io