Sounds more and more like the learjet flew into the top of a very strong updraft at 41k ft and encounters icing which under normal conditions isnt really possible that high up ironically because of the extreme cold. At that height any lose of control is very difficult to recover from, any kind of dive would almost instantly overspeed the airframe and from the blurry stills of the aircraft right before impact you can see the tail appears to be damaged which probably occurred early on in the overspeed and prevented recovery. Once the elevator tore off the tail from stress the aircraft had no way to really pull out of the dive unfortunately.
These planes fly very high and therefore very fast, the stall speed at those altitudes is very close to the airspeed they fly at, this is due to lack of air pressure, they call it coffin corner, there is little wiggle room. They tried to actually gain altitude to get out of the updraft due to the icing and probably entered a high speed stall.
