Why the vertical stabilizer didn't come off in flight.
It would sure be nice if someone would run an actual dynamic simulation on youtube of a swept wing airliner missing all of its vertical stabilizer at cruise airspeed. It would be very educational.
Swept wing induced roll rate is very powerful with even with relatively low yaw angles creating significant roll rates. I would anticipate that an airliner in this situation would randomly but inevitably develop significant yaw, and with any angle of attack would rapidly build roll rate. The increasing roll rate would cause an increase in angle of attack and yaw which would further build g while increasing the roll rate further. As angle of attack increases, the fuselage gets more out of line with the roll axis, and centrifugal force is the driver of increasing angle of attack and yaw. In seconds, g loads would exceed structural limits of the entire airframe.
The only way you might hope to avoid the immediate breakup would be to zero angle of attack (but that has its own bad consequences if held for very long).