Oda set up 3 fights in Egghead.
Luffy vs Topman (only gorosei he couldn't hurt)
Zoro vs Nasjuro (sword clash)
Sanji vs Kizaru (Only character to break Kizaru's Laser)
Sanji's Gorosei opponent wasn't on Egghead hence minimal interaction with all 5 of them.
Oda would've had Sanji at least kick Ju Peter, like he did Nasjuro if that was his future End of manga fight.
Similar situation with Mars, neither Sanji nor Franky stood out in that combo attack, if he was a future fight for him he would've played a bigger role.
That's why I'm going with Figarland for now. He is also now "God of Science" which can't be a coincidence as Sanji is "Warrior of Science".