If you take the narrative of Luffy fighting Zoro as a joke but take Sanji/Zoro competition in Little Garden as flat out serious super duper portrayal of insane rivalry, you're just being a hypocrite.
I don't think Luffy = Sanji, I don't think Zoro = Sanji, but none of those portrayals were a joke. The first narrative was to show Zoro's closeness with Luffy during early series, the second one started the long-standing bickering and friendly rivalry between Zoro/Sanji.
Zoro/Luffy's WP interaction was never about rivalry or character, but just power defining narrative in the moment. It wasn't some trash gag scene.