Thats the bare minimum i expect.
He can save that shit for Luffy if they interact, with Zoro he uses his sword.
What people aren't getting is that the Sunny is outside of the lab next to door, these all out war scenarios make no sense.
The Marines need to get on the island and go up to the Labo-phase for any fight to even happen.
The moment everyone is on the ship and the barrier is turned off they're gone, only Kizaru and maybe Saturn have enough plot shield to get there before the crew leaves and this is when Zoro stays behind to have his Ray parallel and stop Kizaru while the crew escapes.
Another scenario is Luffy stays behind and fights Kizaru, Saturn and everyone else but no one cares about this shit and it makes no sense for Luffy to fight the 2 strongest enemies in the arc.
Either the Strawhats escape with no fighting or 1/2 stay behind to buy them time.