What about Saturn, going to watch the fight while eating bread with a fork?
Didn't you read his quote? "Don't let them figure out I'm here", while eating on the confort of his ship.
Saturn can be a fighter, but his likely role here is to take a look at Luffy and get the Seraphims from VP, as he himself has a higher authority and outranks him in the control for the Seraphims.
And even thinking Saturn is outright superior to Kizaru is also wishful thinking, as nothing hints at that so far.