Luffy heard everything that Saturn said to Bonney, he was eating while Saturn was oppressing Bonney.
Use your brain again, why was Luffy eating and recovering to go back to Gear 5?
It clearly wasn't for Kizaru, Kizaru was still down when that happened.
Luffy started eating to go back to Gear 5 and fight Saturn. He even punched Kizaru away this chapter, most likely to focus on Saturn.
You are clearly deluded by your agenda and blinded by your feelings of wanting Kizaru to be above than what Oda is portraying him so far.
Contrary to you, I'm not pushing any agenda, I'm simply analyzing what Oda is doing and explaining it to you in simple words.
I have always sought to understand what Oda is doing in this series and Oda is clearly building the story towards Luffy vs Saturn.
You can disagree with that and say that I'm pushing an agenda if it helps you sleep at night but clearly, you are blind as fuck.