Seems like a lot of people lack reading comprehension and are completely misunderstanding what has happened here. Saturn did not set sail to egghead because he wanted to confront luffy. He did not even know luffy would be there. This is the sequence of events
- The gorosei suspected that vegapunk was betraying, and sent cp0 to assassinate vegapunk
- Saturn set sail to egghead because he anticipated a counter attack from vegapunk, and took kizaru to protect him
- Kizaru later heard that the strawhats had arrived at egghead and said "we will proceed as planned" and requested battleships
Meaning Saturn needed an admirals protection just to face vegapunk
- The gorosei suspected that vegapunk was betraying, and sent cp0 to assassinate vegapunk
- Saturn set sail to egghead because he anticipated a counter attack from vegapunk, and took kizaru to protect him
- Kizaru later heard that the strawhats had arrived at egghead and said "we will proceed as planned" and requested battleships
Meaning Saturn needed an admirals protection just to face vegapunk