Wouldn't a CO event happen relatively quickly?
I think you guys are overthinking this. The most obvious explanation on the male is that he passed out from exhaustion once the CG arrived, and his adrenaline levels stabilized. CPR can be exhausting, especially if you're working on someone you know, which will amp your emotional state through the roof as well.
The female's state could be caused by almost anything. Drowning, medical unrelated to dive issues, rapid ascent, allergic reaction, exhaustion, and so on.
I'm not trying to stop the CO discussion, as it's always worth discussing, I'm just pointing out a simpler, more likely (imo) explanation for the incident.