Again, the fact that Jimbe got involved with Zoro's fight is out of character for him, so doing things out of character isn't out of the question here. Did he attack him knowing he's helpless or did he attack him just because he saw him standing after Zoro's attack because they have to escape as quickly as they can? You have to know the answer for that to know whether Jimbe went out of his way to make sure Lucci can't continue to fight or not.
Regardless of Jimbe's intentions behind the attack, we do know for a fact Lucci was completely incapacitated before Jimbe's attack. I don't know why we're completely ignoring that and only focusing on Jinbe's intentions. If we're gonna care about the character's intentions, why aren't we questioning why Zoro wasn't going for another hit if Lucci is so visibly not defeated?