This guy want to kill luffy .
‘Of course he asking for the fight alliance because alliance are thankful for luffy.
Does alliance let greenbull to kill luffy ?
Kuma want head of luffy . Result kuma fight zoro, vanish ghost girl.Basically it is kuma vs everyone in narrative sense.
caputring robin is only cp0 and gorsei thing.
Simply greenbull came to wano just to kill luffy to make Akainu happy. It is literally simply villain plot.