Episode 11 - UTW-Vivid
That's definitely it. Kugel might not have been a bad man in the beginning, yet it must have been quite a hit to first find a paradise like Earth after the emptiness of space, then find he can't leave the cockpit. So, he can't appreciate the kind of healthier life Earthlings live and might have even grown to resent it in his isolation. Ledo is the opposite, naturally, so I don't think their chemistry will work for long. Especially if Ledo was tasked to bring the dreariness and rule by fear upon Gargantia. The threat of Hideauze is the single thing they share, but even that Ledo is doubting more and more.
I'm not even sure it has to proceed all the way to Kugel's cult decreeing Bevel useless before Ledo will reject Kugel.