Eric - that's possible, and surely on some level, true. On the other hand, your brother-in-law, is suggesting that there is a way beyond the Heisenberg Uncertainty Principle, in which any measuring device we use to determine the nature of an entity effects the nature of the entity. (Which we may be seeing here regarding all these definitions of aiki).
The observer effect is not actually related to the uncertainty principle. Heisenberg offered the observer effect as an incorrect explanation for the uncertainty principle. He did not understand that the difficulty he was having simultaneously and precisely observing position and momentum in particles was due to inherent properties of quantum systems.
The observer effect is not inescapable in most observations, and in systems in which it is a factor, it can be adjusted for by including the observer in the system studied. Even in quantum mechanics, in which the effect is inevitable and large, the effect is understandable enough to be controlled for.
There does seem to be a huge and necessary observer effect in human interactions, and human psychology is such an imprecise field that providing controls is very difficult, impractical in daily, non-experimental interactions.
I do take your point and agree with it about the observer effect and the aiki wars, I am just so much of a geek that I cannot let a common misconception about the uncertainty principle lie. The brother in law is not rewriting physics.