If this graphic helps by showing something that could be relevant then I don't see the problem.
This graphic don't help at all .. the graphic show only the temperature at the top of the clouds ... .. and the aircraft was not at this altitude !
It's indicated in the caption ...
Temperature of the top of the clouds by satellite mesure
What is needed or relevant is this (for the AF747) from Tim Vasquez
Air France 447 - AFR447 - A detailed meteorological analysis - Satellite and weather data
Tim Vasquez's webpage