He is not the underdog here lol
He is just running away from someone, who is litearly a one shot.
Luffy being a Yonkou, means he is that strong, that he should not run away from a fodder.
Doesn't even take a second to take care of him, why instead of fucking run away?
Not a personality change, his title as a Yonkou represents his level, he shouldn't be running away from people like that.
Even before, if there is a fodder, he would just one shot them.
But no, lets waste panel time on that shit...