It was the Indonesian transport minister not a journalist that claimed that it climbed "too fast", so the assumption is that the "old radar data" has been confirmed somewhat by data already gleaned from the recorders. It's also stated that it stalled which they would probably know by now. Also updrafts do not necessarily bleed airspeed but zoom (speed for height) climbs always do. The pitchup into a stall scenario during the climb to FL 340 now seems most likely for whatever reason.