It’s bad write, man. Sanji has this desire to serve, what kind of "king" is that?
What about Sanji’s dream? Imagine if there were a return to his roots, a return to that dream, if Gaban mentioned something like that, and we got to see that look of pure joy on Sanji’s face. Sanji’s dream, his own personal goal, hasn’t been mentioned ever since.
I was on the same page as you until I watched morjs video about conqueror haki users. He did it after mihawk talked about being ones self.
Sanjis coc as he explained should come from his desire or chivalry. Because even as is. We don't have a clear cut purpose on what sanjis role is. He said to be luffys shield but what is his all encompassing dream? And I simply think it's to always be chivalrous.
All coc users embodies their ideals.
Shanks ideal is to protect his comrades.
Koby embodies being truthful/Honest
Zoro embodies prides/desire for bis goal
Sanji embodies chivalry
Katakuri embodies being the imahe of being a big brother for the protection of his family.
Doffy embodies destruction of all that oppose him.
Etc etc