Do people forget that the SHs are mostly some 18-20 years old brats?
He was introduced as being a prick with a bad attitude, but, also, a kind hearted person who refused to let someone starve, no matter if an enemy, due to empathy.
He, at the time, was buried in a deep and unhealthy sense of debt towards Zeff, that eventually made him give up on his own dream to find the All Blue (a tendency that would carry on throughout the rest of the story until mid-WCI), later becoming really inspired by Luffy and Zoro (reflected by him wanting to take Zoro's place during the Kuma thing, in order to protect Zoro's own dream).
A gag doesn't change that.