Why didn't he just punch Saturn away?
Why does everytime Luffy is on panel, he is focused on Kizaru? So far Franky, Sanji and even Kuma had their lick on Saturn, but not a single character on the island aside Luffy touched Kizaru, it has to be Luffy.
First, these are short spoilers, we don't even fully know what happened in the chapter.
Kizaru and Saturn were close to each other last chapter.
In Pew's spoilers, they plan to annihilate everyone on the island.
To prevent that, Luffy comes and punches Kizaru away.
It's not a "round 2" like you claim, it's Luffy coming back and punching Kizaru away like the spoilers clearly mention.
Will it lead to a round 2? Maybe but use your brain for a second.
You have Kizaru and Saturn but who is clearly the main villain of the island? Who is Luffy going to focus on?
Saturn.
Kizaru will come back but he will be stopped by somebody else.
The current chapter changed nothing to what I was saying.
You can't merely jump to the conclusion that this punch will lead to Luffy vs Kizaru round 2, period.