Queen: A human burning!? Don't be stupid!! It's not like you're from the Lunalia tribe!!
Sanji: It's possible with my passion...!! My passion will exceed even the temperature of flames/fire!!
Sanji: Sea beast meals are my speciality!! Damn Dinosaur Bastard!!
it doesn't matter that you are fighting head on when your opponent has a wierd ability, for example Fujitora caught Zoro off guard with his Gravity , or Kaido was caught off guard by Kinemon Fire cutting ability and Raizo Ninja scroll, or Sanji getting caught off guard by parasite. Eat the fat L
Zoro doesn’t need to improve his swordsmanship in his main fight of the arc as along as he does improve in the arc as whole it’s settled. And guess what Zoro did due to learning Kin’s flame cutting technique.
In fact, he does.
His dream is to become the WSS, his role is to be a combattant therefore his development towards his dream should be during his fights. Which is why the Mr.1 and the Braham fights made sense even tho they are not a swordsmen.
But if the fights in themself do not help him towards his dream why is he a combattant? He should have another role in the crew and just fight time to time like the other strawhats.
We did not even see how he mastered this ability. You have a whole arc in the land of the samurai and Zoro did not learn anything from them apart cutting fire which he done off-screen and it is somewhat good?
Imo Zoro is just taking the piss when he says he will bite off King's throat but at the same time that statement also shows his dedication to not lose again even it means he'd do something he wouldn't ordinarily do, so basically he'd do it if he has to if it means winning.
Or at least that's the impression I get from him.