Many clues point to a bomb in the vicinity of the port (left) aft (rear) lavatory.
Interesting analysis.
Obviously deliberate - whether internal or external. But we shouldn’t ‘jump to conclusions’. We do not know if it was ISIS, even though Russia is pounding the crap out of the Islamists in Syria and that flight was over Muslim Brotherhood lands in Egypt.
It was likely the center fuel tank catching a spark from a greenhouse gas that would not exist if Americans would simply do without air conditioning.