Well, if the stuardess couldn't reach them on the intercom and couldn't get them to open the door, then a reasonable person might assume that they were unconcious. If this were the case, one would expect more than one communication from the passengers though.
Islamofacists will take credit for this, whether they did it or not, so that really can't be the key.
Hopefully, more facts will be forthcoming. I'm not saying anything other than that airplanes did crash before islamists started bringing them down.
Maybe one of the pilots was a bad guy.