You appear to be forgetting the effect of the sideslip. At 30 degrees of sideslip, there is considerably more drag, considerably less lift and somewhat reduced thrust. As stated in the report, the ATSB were unable to quantify each of these effects without going to considerable engineering and modelling work - due the manufacturer not possessing the necessary data.
The ATSB didn't do simulation, modelling or fight tests because they say it was outside the scope of the report, not that it was too expensive. How they can say it was outside the scope of the report is beyond me. And it is unknown if the manufacturer had flight data or not. The ATSB did not ask Raytheon. The list of organisations that were asked for contributions is on page 66. Raytheon are not listed. Once again, something that defies logic.
You claim that you could hold the rudder forces for a minute. Have you ever tried this in a real King Air or a simulator?
The SIM pilot said " the yaw on take-off was manageable". The rudder force required was not quantified (another report oversight). One KingAir pilot on this forum says it was manageable. I have it from 2 pilots that flew the subject aircraft that they have flown it with full rudder trim without difficulty
All the pilot needed to do was hold opposite rudder for 1 min - at which time he should have been well above 1500ft which would in turn have allowed time for diagnosis.