I take your point and I see why my phrasing would lead to the conclusion that I am affirming that he lost the debate.
If I were a better writer I would have been able to convey that, when I say "failing to 'win' the debate," in my mind I'm citing what the media and various pundits are accusing him of. And not what I think.
I agree with Heather Cox Richardson and Ruth Ben-Ghiat who both said that wasn't even a debate. And in that sense I feel like if I say he "won" then I'm condoning it being called a "debate."
My fantasy wish is that the majority of the American people would have been able to come together and say to CNN "we reject your calling that a debate."