idk maybe cause Chinjaos he was a rival of both Garp and Roger, Hasshoken master, he was an exleader of the Happo navy, a pirate of legend and goal is to defeat the strongest marine to ever exist: Garp, a conqueror who has shown possibly one of the single greatest showings of CoC and haki utilization in general while had to train and destroyed 8 mountains in the process to prep for their final clash... katakuri showcased and demonstrated dominance and "perfection of the meaning of being strong", and being unrivaled and undefeated his first loss came from Luffy another conqueror who at that point in time was weaker than him but lost in ideologies and moral where as luffy demonstrate unwavering willpower and luffys strength came from determination and never questioning his weaknesses rather reflecting on how to overcome them mid battle.
not all conquerors are built the same but the point in the matter remains does sanji actually deserve CoC other than needing it for plot against HK/Gorosei/Imus forces or does he actually deserve it?
"Chinjao was a rival of both Garp and Roger."
Sanji is a rival of Zoro. Also Moria rivaled Kaido at one point, does he have COC?
He is a Hasshoken master.
Sanji is a black leg style master
"He was the former leader of the Happo Navy."
So is Sai, a member of the grand fleet, who is vastly weaker than Sanji and holds an inferior position to him.
"He is considered a pirate of legend."
So is Gaban, Sanji's parallel. Unless you think a prime left wing of Nika won't be a legend?
"His goal was to defeat the strongest Marine to ever exist."
No, that was petty vengeance after his head got flattened. Unless you believe Chinjao only unlocked COC after the age of 48. Also, we already established that goals don't determine if someone will have COC. Ace wanted to make Whitebeard king, Sanji wants to make Luffy King, that's an active goal of Sanji's.
"Katakuri demonstrated dominance and “perfection of strength”."
Only that isn't the case because he is weaker than many other characters with and without COC. He was a big fish in a small pond.
"He was considered unrivaled and undefeated before his fight with Luffy."
Yes, then he lost to a Luffy that was getting one shotted by Yonkos. How do you think a fight between prime Sanji and a 48 year old Katakuri would go?.
Again, you have nothing.