Zoro on the roof, half-dead with the remnants of his strength, really gave out everything that was. BUT. before realizing that it was necessary not just to feed enma, but to give out ALL the haki in all the blades. At that time, Zoro had not yet "studied" the new release technique in his haki. Zoro on the roof = Zoro on this frame.
the situation is the same on the roof and here. Zorro is enough to feed Enma, but it's not the King of Hell, the King of hell is a complete lifting of the restriction on the release of haki and this technique is done by the swordsman himself, not Enma.
you can deny the words Zoro said on this frame, but it's clear as day that Zoro gave the sword enough haki at this moment and on the roof, but this is not enough for the king of hell mode. The King of hell is an independent infusion of haki and Zoro can do it with any blade. There are no more than 7-8 such swordsmen. Zoro Mihouk Odin Reilly Gandhi Shiryu Shanks Ryuma. Perhaps Fuji