As usual, Turnbull, you've come to the crux of the discussion.

We want to believe that Vito was a "better" man, and we romanticize his actions while we "look down our noses" at how McCluskey acted, but I believe that Vito and McCluskey were cut from the same cloth.

I think McCluskey's realization that he'd have to return Sollozzo's money (because he didn't properly do his job of clearing away all the "hoods" guarding Vito) was more of a business decision rather than some ethical judgment. McCluskey knew there'd be more opportunities to do business with the Mob, and he'd soon regain that large payment plus some more, but only if he returned the money first. Vito would have come to the same conclusion, and acted the same if the shoe was on the other foot.