Uplinker
Yes, I know the Captain was on his break. A break he began immediately after engaging in discussion with the two co-pilots about the fact they were entering the ICZ and were expecting the associated turbulence and icing for the next 15 or 20 minutes. For the Captain -- responsible for the safety of the aircraft -- to decide not to wait another 20 minutes to start his sleep, is a contributory factor.
Even more damning is the fact that he spent the previous night partying in Rio and said he had only an hour's sleep (his own words). So he had slept for an hour in the previous 36 to 40 hours (approximately). Whether his actions were simply a reflection of his own attitude to Captaincy and leadership, or a reflection of an Air France cultural attitude, I don't know.
Lastly I'd also suggest possible cultural bias for the BEA not to have considered the crews' partying and lack of sleep in Rio worth mentioning in the report, at least in the context of fatigue.