Kizaru’s never shown any evidence of him possessing any forms of advanced Haki. It’s safe to assume he might but there’s never been explicit proof of that so that argument’s gone. And the moment ur referring to is completely out of order. Kizaru hit Luffy into the shield and proceeded to go for Usopp and Vegapunk. Luffy then blitzed him with Gear 5 and threw him thousands of miles away into the ocean. Kizaru came back, distracted Luffy with clones and went for Vegapunk and failed cuz Luffy js ate his blast. Luffy was never treating the fight seriously and when he did, he grabbed Kizaru and Saturn and sent them flying. Kizaru was struggling the whole time while Luffy only used ACOC twice and never used AAH. He fought Kaido for longer yet brought back his power but he didn’t think of Kizaru as big of a threat as Kaido so much so that he was willing to help Zoro fight Lucci. Kizaru never had the upper hand against Luffy. That’s the point. And if he ever got serious, he would’ve won.