Even in traditional athletics, it's well known that the body can use different sets of muscles, or a different balance across sets of muscles, to accomplish the same movement.
Going back to my weightlifting days, a bench press can depend primarily on the pecs, anterior delts, triceps, or lats. A common limiting factor is depending too much on delts and tris and not getting the pecs engaged. The common fix for this is imagery: "Imagine there's a rubber band connecting your elbows. As the bar comes down, you're stretching the band. Then as you raise the bar it's pulling your elbows together."
Similarly for squats, depending too much on quads and not enough on hams and glutes. There's a set of visualizations to help lifters get the posterior chain involved.
So I don't see the IS imagery as magic or particularly unusual. Any time you want to get the body to move differently, it seems, people use visualizations to help create the new movement patterns. And the visualizations rarely have anything to do with physics.
I wouldn't go that far. While there are conceivably a nearly unlimited amount of muscle recruitment patterns that can be trained, the number of actual muscle groups you can leverage for a specific movement, not so much. Doing things like spreading your knees while squatting can bring some assistive tissues into the equation, but for the most part movements are mediated by the major muscle groups which are already cleverly positioned for exactly that task.
Even if you could train to not use those muscle groups for movements, which you cannot, it has never been satisfactorily explained to me why in the would I would not want to use my body in the way it was designed. I am guessing all of the double speak about "western", "athletics", and "conventional" boils down to different and effective recruitment patterns more than it boils down to actually using different musculature. That said I can imagine, given that fact that almost no aikidoka could squat their way out of a wet paper bag, people using profoundly incorrect musculature for even the most simple tasks, but that is more of a remedial discussion. Obviously there is great room for improvement no matter where you are in the game.
Taking the pseudoscience angle one step further, we have to consider that it has been strongly recommenced here at times to use non-contractile tissue as an alternative to "conventional" movers. It is quite reasonable that "feeling" like you are using such tissue may result in a non-standard recruitment pattern that could have martial application, actually attempting to use non-contractile tissue for movement will result in no movement, a state with little martial application.
This situation is exactly why people often ask for better clarity on the ideas presented here, particularly those that have the ring of woo.