Haha. I thought the point was, in this anime adaptation, that he ripped also a piece of the man's shirt and the heart was inside it, like in a pouch. It surely didn't look like a bare heart at all.
But yeah, Killua kicks ass. I didn't remember Leorio sucked this much, though. He did achieve to get a handful of the girl's body, but that was only he, with the team watching from afar. Kind of unfair. I'm sure he still thinks it worth it, in any case.
You shouldn't have such expectations in the first place. He's not that sort of a personality. In fact even Leorio shouldn't be. The Hunter exam has shown from the beginning it's not any boy scout club. It's a mission where you are constantly and consciously risking your life. If you accept risking your own life, you must accept others risking theirs as well, to avoid being a hypocrite.