I've come to see that not being moved isn't the point; it's a byproduct of learning how to manipulate the forces trying to enter my body and adversely effect my mind/body coordination. Practicing the exercises allows me to experiment with dissipating the force, letting it in and sending it back to uke amplified or stopping it at the point of contact.
Which is exactly the problem, being immovable isn't the point, but the structure of the classes in the Ki Society and offshoots encourages the assumption that being immovable is what you are learning to do (it's not, but the assumption is the problem). When people test me I'm quite capable of moving my feet, wiggling my hips, even jumping up and down without them being able to 'move me', all I've found that means is that people think they need to be 'immovable' like me when I try to teach them how. They're immediately working from a false assumption, and therefore setting themselves the wrong criteria for success.