Currently, the only option of preventing malicious admin users from deleting a cluster with all its backups is to enable a backup compliance policy. However, this policy is quite the beast with complex processes and guarded by a single user account (which could then as well be the malicious one).

It would be good to have some less impactful way of protection against malicious users.

For example, when deleting a project in Google Cloud, an email is sent to all project owners and the project including all of its data can easily be restored within a period of 30 days. This does not impact regular operation but also effectively prevents malicious users from causing permanent damage.