The first responders did an amazing job, IMO. Truly heroic.
I don't think we should assume permanent damage. He was in very good shape, and relatively young. He was not in grave condition. He wouldn't have been flown or considered for the treatment in NY if he were not at least in critical condition. His color was good - his lips and face had a surprising amount of color (per the NYPost photo). Many have recovered fully from CO poisoning.
I'm just saying this because it's not an automatic assumption that he will be 'brain dead' or anything close to that. (Also don't know how much he can act that part, vs what doctors can test independently.)
We'll have to wait and see what the doctors say.