oj I'm sorry but your theory is just wrong. This basic Newtonian physics, bodies at rest tend to remain at rest, for every action there is an equal and opposite reaction, etc. So the nano-second before the pinion turns nothing has happened, but when it does all the parts try move the least amount and in the direction of least resistance. Suspension theory is all about directing the energy, usually described as torque to do the most work with the least loss such as wheelies, twisted frames, too little tire pressure.
To your drive shaft example and gyroscopes: a gyroscope works when it's spinning not when it isn't. If you pull the string on a child's top it doesn't go dead straight it moves around until it reaches optimal speed and then settles in until it loses momentum; same with the drive shaft. Pinion angle adjustments are one of many settings that are made to effectively channel the torque efficiently and to minimize damage from that torque working against, in this example, the u-joints.
If you want to test this set up you car with static positive pinion angle and set up a video recorder as shown in the You Tube clip. I suspect you'll get the same rotation of the housing but likely encounter some other problems up to and including u-joint failure.