If Ashura is retconned to be conqueror's, if anything.
Not like it would matter, anyways: one is becoming the supreme conqueror among conquerors, and that's not Zoro; one has the factually higher mastery of haki right now (future sight, level beyond of armament), and that's not Zoro; one wouldn't have left East Blue without the unstoppable will of Luffy carrying him, and this time that's indeed Zoro.
But, not surprisingly, you focused on made up power levels instead of reading the story. Nobody with a bit of honesty would actually read One Piece and put Zoro's will above Luffy's, he's the main character and therefore the person who embodies the themes of the whole story. His ambitions are higher than Zoro's, his willing attitude actually moved Zoro out of his confort zone, Zoro found an ambition greater than his own (as per Mihawk's words, clearly referring to Luffy)... and, on top of that, he represents supreme freedom.
And nothing in this story is a more potent example of strongest will than achieving supreme freedom, which in Luffy's mind not only means to do whatever he wants but also to defeat any force opposing such freedom ideals —which is, by the way, the reason why he aims at becoming the strongest person in the world, and this, again, includes Zoro.