Not even you believe what you wrote. I'm sorry.
Sanji's exoskeleton has a clear indication on when it's active (the eyebrow switch), so yes. Sanji can still be in base.
Yes, for now Sanji IF is Sanji's stronger mode/form but the attack he does when he is in this form matter more. So in this case he did not use his strongest attack for sure. Same we can say for Luffy.
By the way this chapter sure it's super interesting and still in this forum the only thing that is discussed it's stupid power levels that Oda does not even think about it a lot.