Doflamingo wasn't frozen to the bone. That's almost a fact. But it can easily be said, that it had more to do with Doflamingo than it did Kuzan.
Which is why it was definitely positive portrayal on part of Doflamingo, being able to break out of the ice however he did it, (imbuing COA before being completely frozen, sounds pretty logical), and he did it while not even facing Kuzan, he got attacked from behind.
He was still panting which shows it probably required some effort and/or because he was cut off from oxygen (but WB was as well, and he wasn't panting). Oda probably did that scene very carefully considering Doflamingo's arc was coming up, he managed to hype Doffy while still giving Kuzan the portrayal edge. He managed to avoid either of them looking bad.