Okonkwo spent twelve years as a shipboard engineer before accepting a commission. The detail matters because twelve years in the bays, before becoming an officer, produces a different kind of officer than the standard commissioning route. He knows what the work looks like when it is done correctly. He also knows what it looks like when it has been signed off as done correctly and has not been.
The commission came at the point where it became clear that the Fleet's engineering standards were being set by people who had not turned a wrench in years. Okonkwo had opinions on this and, unusually, had accumulated enough institutional credibility that his opinions were invited rather than managed. He wrote two fleet engineering protocols that remain in use, both of which he describes as corrections to things that should not have needed correcting.
He and Admiral Artemis know each other from overlapping Engineering Corps postings that predate either of them holding flag rank. Neither has publicly discussed what, if anything, was said when she appointed him Chief Engineering Officer. The Engineering Corps functions well under his command, which is either an endorsement of his approach or an indication that he and Admiral Artemis think about engineering in similar ways, or both.