@GetsugaZoro:
You cant compare him to Spandamm Spandam is actually a bad guy Hannyaball isnt bad at all he is greedy and wants to be promoted and all but his sense of justice makes him a good guy actually.
Also, the shift of Hannyabal's demeanor from being someone who is willing to lie to move up in the ranks, to upholding the integrity of Impel Down was rather believable.
Hannyabal was starting to focus less on his duty and more on moving up in the ranks because Impel Down's impenetrability was upheld so well, that he felt he didn't have to worry about it. But the crisis to the point in which Blackbeard invaded knocked him back to reality once Magellan proved he was more capable both in organization and containing the disaster.
That's part of why the guards cheer him on–because he hadn't been taking his duty as vice warden nearly as seriously up to when Bon Clay got to him.
Actually, the filler flashback seems to be an allusion to Bon Clay posing as Nami and pretending to undress. It makes him seem much more incompetent at that point in the anime.