Kizaru is mentally nerfed from having killed his long time friend 30 seconds ago
This is what the voices in my head are telling me right now
I hate it, but I think Oda is pulling a Snape and Dumbledore.
How many times did Kizaru miss attacking Vegapunk? A good amount, probably in the double digits by now. This is the guy who had enough accuracy to snipe Ace's key in half when it was in Luffy's hands in Marineford.
When did Kizaru actually get a hit in on Vegapunk? Right after Vegapunk told Sanji he didn't want to leave the island anymore, and that there was something he had to protect.
Kizaru could have easily stabbed Sanji here if he had the ability to kick him. So, why kick him away, only to THEN stab Vegapunk?
Kizaru wanted to help Vegapunk escape, but was told by Vegapunk that if Vegapunk became mortally wounded, that Kizaru needed to kill Vegapunk to trigger the Deadman's Switch on the Worldwide Annoucement, and then keep the announcement from being stopped.
Vegapunk told Kizaru ahead of time to do his job, so that no one would suspect Kizaru was in on it, but, Kizaru's been holding back and using Future Sight to try to avoid Vegapunk's demise. Kizaru's been getting more and more depressed as he realized there was no real way for him to save Vegapunk.
If Vegapunk really big-brained the whole thing, it's possible he sent a SOS out to the giants, and has been trying to stall for them to arrive so he can send out his big message.
Think back to what Shaka said:
Shaka/Vegapunk knew that once he revealed the truth of the world, he'd be killed.
It's possible this worldwide transmission was his endgame the entire time and Kizaru was working towards it.
Fuck that I just want Awakened Kizaru vs Gear 5 Luffy.