He can defend the "can't breathe" thing. When a person says they can't breathe, they can. It's the only way to speak. Chauvin will say that because Floyd said it 27 times he thought he was lying.
If he assumed Floyd was lying, he probably thought he remained dangerous. So he needed to remove the woman from a potentially hazardous situation asap. The threat was harsh but his intent was well-meaning.
Not saying this is what I think his state of mind was. I don't know. But he could argue it.
Instead, he's saying, no, I didn't kill him. It was a coincidence.