... the SIM pilot is not reported as having made any comment on the controllability at the speeds exhibited in the incident. The SIM pilots comments are that the yaw was manageable at lift off, then challenging, then uncontrollable after an unspecified period with the aerodynamic load at 140 knots and above. The aerodynamic load can be expected to increase with the square of airspeed - so the rudder force required to correct the LH rudder trim at 140 knots will be very different than at 108 - 112 knots.
Old Akro,
I think you have oversimplified the situation. There are many reasons why the simulator performance would be too dissimilar from the real aircraft's performance to draw reliable conclusions. Being a level D simulator means that the control forces (e.g. rudder forces) for regular assymmetric flight would be accurate, but for the case of symmetric flight with full rudder trim, it appears there is no certification requirement for accurate representation of flight characteristics and control forces (based on my limited research).
For a simulator to faithfully exhibit those things would require the manufacturer to possess the data for them, and from my reading between the lines of this report, it appears this manufacturer does not.
And, I would suggest you are not accounting for all the aerodynamic effects that were contributing to the yaw moments that morning. The fin/rudder would have been contributing a nose left (NL) moment, sure, but there was also a significant NR from the fuselage body aft of the CG. But at such high angles of sideslip, I believe the fin would have been somewhat stalled, thus reducing the NL moment.
So, nowhere near as straightforward as you suggest to make an armchair adjudication on the controllability of the aircraft that morning.