Communication isn't the value he's generating, and he's not causing harm through deception.
Companies employing me all my life have lied by omission to me, about my value to the company and how much more they benefit from my work over and above my salary. Is that ethical?
He is causing harm through deception. The bugs he produces as a ruse have to be checked for and repaired by other employees who might not need to check the output of a well tested automated solution at all.
Nope, you got that wrong. He reported the workflow (possibly extended on it in a comment) as he generates a draft, others check that for bugs, he generates a final version ostensibly based on that bug-checking. Intentional errors are introduced only into the draft, not the final version, so even if his colleagues miss any of them, they aren't in the final result.
So nothing _has_ "to be checked for and repaired"; as others have commented, he's just doing his part to help these colleagues have something to do, too.
Companies employing me all my life have lied by omission to me, about my value to the company and how much more they benefit from my work over and above my salary. Is that ethical?