How is an un-self-aware manager ever going to be effective at anything?

The author notes your objection, and addresses it:

"There’s a fine line to be walked between managing the pull request process and micro-managing it. What happens within any specific pull request is the domain of the team so you should resist the urge to intervene frequently within the process itself. The behavioural trends in the process are your domain and if you’re running a meta-review process well your work will be predominantly behind the scenes."