Duchess Mesunu sought to restore her position within the Imperial Navy.
Menilman, on the other hand, was a meteoric rising force within the Imperial Navy.
The contradictions between the two were imminent, and their conflict might escalate into an intense situation at any moment.
In the early stages, Menilman even had to rely on robbing pirates and Charles's financial support to secure his footing, which shows how much this senior was ostracized and suppressed within the navy.
This suppression was almost certainly from Duchess Mesunu.
Now that Duchess Mesunu had no way to deal with Menilman, perhaps upon hearing of Charles's assistance, she turned her attention to squeezing a "soft persimmon," with junior rivalries and jealousies being nothing more than minor details.
Perhaps Duchess Mesunu wanted to strike at Menilman but was unsure of which target to choose, and Mister Alans Cook provided her with that target.