I think you’re vastly underestimating Momos importance here.
1. With Momos death the entire people of wano lose hope in the battle early on. This means Tama would lose hope along with them meaning no Gifter uprising meaning all the fights would have ended up in losses. Remember the alliance didn’t know Hiyori was alive. Momo was their one and only dream.
Also Tama's part is completely fake. The person who maintains Tama's will is Luffy.
2. Even if they don’t immediately surrender, with Momos death Luffy would not have been able to make it back up to Onigashima meaning Kaido would’ve ended the alliance personally and killed or enslaved everyone
3. Finally, even if Luffy finds a way back up to Onigashima, he can’t fight all out because his Bajrang Gun would’ve caused the explosions in Onigashima to explode killing everyone
Momo was the second most important member of the alliance, and in the eyes of many was the most important because of his role in the war as the hopes and dreams of the samurai. Momos influence outweighs kids and laws.
Momo is not the second most important member, much less the first.
Rather serious;
- Luffy
- Zoro
- Law
- Kid
- Tama
- Momo
And you could even take Sanji out of the equation and the alliance might have won.
Finally, there’s also the fact that without Sanji there’d be no samurai alliance in the first place. He saved the three most prominent members of the Nine Red Scabbards as well.
1. Kinemon - Leader of the Red Scabbards and organizer of the rebellion would never have left punk hazard if not for Sanji (which also means Momo wouldn’t be traveling with the straw hats)
1. Kinemon - Leader of the Red Scabbards and organizer of the rebellion would never have left punk hazard if not for Sanji (which also means Momo wouldn’t be traveling with the straw hats)
2. Inuarashi and Nekomamushi - The leader of the Minks see Sanji as the savior of the minks as well.
Again, i don’t think you really understand the fact that the entire alliance was indirectly built on small dominoes Sanji set up. And if he didn’t do what he did in the arcs leading up to wano, the alliance would’ve never been formed and the straw hats would be running head first into a fight with Kaido with just the heart and kid pirates.
Realize that of everything you have said there is only one thing that is really valid. Save Momo.
But it pales in comparison to Zoro's input.