The rudder probably won't come off. Only a Boeing test pilot can tell us if full side slip maneuvers are tested at high altitude.
Do a 360 in 75 seconds at that altitude? That's laughable. We don't do 3 degrees/sec at altitude so there's no way it's doing 4.8 degrees per second in a flat turn. And I wouldn't be surprised if spoiler drag makes the a/c turn in a direction opposite to the rudder deflection.