The use of Facebook, Twitter and other social media sites for official announcements is now well established. The reason for using these sites is that they are equipped to handle millions of requests per second and can adjust their capacity to respond. Government networks are usually much more limited in their capacity to handle requests and cannot scale up beyond a certain limit. This means that a constant barrage of enquiries to official websites would result in most requests being met with a "Server not found" error message.
A 90 degree turn off the flight path is a standard manoeuver when initiating an emergency descent following a depressurisation or other incident. The idea is to maintain separation from other aircraft that might be flying at different altitudes on the same airway. So an indication that something may have occured that resulted in depressurisation, but no more than that. As the aircraft descended the range of any radio transmissions would also have reduced drastically, so it is unlikely that a distress call, if made, would have been received.