I agree with you fully. You gave a very good account why it is important to rest the arm on an armrest when flying glider aircraft. The same can be said about fighter aircraft and Helicopter pilots. All the fighter pilots rest their arm on their thigh while handflying with flight stick and cyclic stick. Yes , Pilot induced oscillation can be eliminatated when arm is rested on a supporting structure.
No wonder Airbus made a unique armrest with height and angle adjustments for all their fly by wire aircraft.
The yoke has lots of tension and large range of travel. The Boeing yokes are back driven and duplicate the feel of a cable aircraft to certain extent. They are not sensitive like a sidestick.
Do you think pilot induced oscillations can happen in a Boeing jetliner yoke ?