You misunderstand, (continued) runtime is dependent on the ability to deploy. For instance: a vulnerability is realized or a customer needs something (availability, feature, who knows), you'll appreciate handles under your control. Service can easily degrade, without.

I've done this same thing, GHA as a control plane. It was for people who could wait; the actual operators regularly skipped the middleman. Preference or necessity, take your pick.

Runtime is separate from deployment. An incident in your deployment infra doesn't affect production. The fact that you may have to deploy to change what's live is what defines it as an incident, but it's still a different thing from a production incident.