I think this aircraft broke apart due to cabin pressurization causing structural failure to erupt, starting in the tail. I could be wrong but I don’t sense a bomb or missile were in play here.
Most likely scenario at this point, data recorders should reveal much more.
Even though it was in that bad zone, over Sinai?
When I first looked at this, I though maybe when the lost communication, they turned off the transponder. Wonder how secure the cockpit was.