Hard to say, as much as retards downplayed Sanji, hes actually the only one, outside Luffy and Zoro, that actually fights the big dogs of the arc
As much as people clown the HKs, they would murder non M3 SHs, thats a thing Oda is trying to tell: Luffy, Zoro and Sanji are cut above the rest
The fighting argument cant be used for Usopp and Nami because they're not fighting someone that requires usage of CoC
IMO if Usopp is one, thus bound to unlock it, hes doing it after the story ends, hes not strong enough to showcase it rn, so it would make sense for him to display it when hes a captain of his own crew. Nami, on the other hand, is not one, so not showing it not even EoS