The idea that the "earth" is pushing anything up - is incorrect. The Earth "sucks," literally.
That pushing up is not occurring. What is occurring is the releasing of the temporarily-stored positive energy. If you squat down, and then jump up - the power is not coming from the earth. It's coming from the stored energy in your legs that you compressed when you did the squat. And the energy is not released up. It's released down. That why we go up. The energy is drained - most effectively - and "in as pure a form as possible" through the decoupling of the body and the earth - through the inverted cones created by mainly the toes. And out of the toes - mainly at a point on the bottom of the big toe.
The earth only pulls us downward. It is the human nervous system response to gravity that "pushes" us upward. This is easily seen when you take an infant who is lying on his back and pull his hands forward so that his weight moves fully onto his feet. At that moment, both of the infant's legs will fully straighten and his spine will lengthen fully with his head "level" to the horizon. Moreover, this is a sudden and powerful movement, almost like magnetic repulsion. This process begins before the child is able to stand independently. It is an unconscious and involuntary nervous system response.
I believe that is the point where the human body translates the downward pull of gravity into the horizontal power of jin. But jin remains within the body and it does not allow the attacker's "energy" to enter the body because its nature is "warding off" or "repelling."
Have you attended any of the seminars you cite, with Mike, Dan, Ark or others?