You're making a lot of assumptions in order to reach that conclusion. Mine is as straightforward as it gets, Luffy dealt the final blow, Luffy can reactivate g5 or simply recover, using it just leaves him exhausted, it doesn't knock him out.
Redon usually mentions it like with Lucci he straight up said “he goes white eyed.”
If Kizaru isn’t KO’d but Luffy is exhausted to the point he’s a sitting duck that’s a win.
It’s like with Doffy and Luffy in round 1 at Dressrosa.