Kizaru didn't want to spend time fighting or defeating Luffy. He pushed Luffy aside and went for VP first chance he got. He's all about the mission and following his orders the way I see.
Being grabbed by Luffy's giant hand is a massive L. Although same goes for Luffy getting kicked aside, he should have grabbed the leg or something to not fly away.
Kizaru has fighting power in him, but he doesn't care about the fight as much as some readers.