To borrow a term from Senator Geary, I'm going to amplify a bit:

I think you can draw parallels between this killing and the Khartoum killing in GF1. In both instances, a brutal death was used to pull the target in line, but more importantly, the target had previously insulted the Corleones. And both targets had treated females as disposable sex objects -- Woltz with the young movie star, and Geary with the prostitutes.

Had Geary taken a reasonable bribe for helping the licenses along, I think there would have been no issue. After all, Vito probably had all those politicians in his pocket that same way. He was just a two bit hick politician on the hustle -- if he were smart, he wouldn't have named his price in such direct language, without a middleman, and especially in his intended target's office. Apparently this idiot never thought the room could have been bugged or the conversation recorded.

But then Geary got exceptionally greedy and demanded a ridiculous kickback. Then to double down, he personally insults the Corleone family -- both in his boat house diatribe, and his "Core-lee-ON" vs. "Core-lee-on-eeeee" pronunciation. That's what probably sparked such a bloody measure to get Geary's compliance.

Something else with Geary that bugs me -- aside from his pro-Italian monologue later in the film, he was really useless to the Corleones. Unless Questadt had a super secret witness list that wasn't shared with the rest of the Senat committee, you would have thought Geary would have tipped Michael off that Pentangeli flipped.