"Here's one for the crew. On a forward step after the heel lead the man lower the toe to the foor imediately.
The lady at the extension of her stride will only lower when her moving foot is level with it."
Actually, if you look carefully you will find that they come very close to lowering together.
"Simple the man bends his knee after arriving on the supporting foot forward.
The lady also bends the knee forward, which is in the opposite direction to the man."
Not really, because the lady is also turning her standing leg, which means that her knee is no longer moving in a direction opposing the man's, but is at least halfway to matching his direction.
"The reason for this is because the knee can only bend one way and that is forward."
Yes, but what direction "forward" is happens to be in the process of changing during that time - somewhat by the turned in placement of the foot, then continued as the weight rolls across the foot to the inside edge.
"The lady does not lower her heel to the floor untill the moving foot arrives under her body.."
No, she must do it when her body arrives on the foot.
"If it is done any other way the ladies weight will pull away from her partner."
Not really, because the body weight is almost over the foot already by the time the foot is actually placed. If they've really sent the body into the step and aimed through it, the necessary motion is going to be full enough that it's going to be pretty hard for her to fall ahead of it by neglecting to resist with her arriving leg. She could still of course ruin it by letter her upper body go over backwards, but that's a poise problem, not a foot action one.
But the problem you describe IS much more likely to be an issue on step 1 or step 4 type actions following a foot closure lowering though, because precious few couples manage to actually project their bodies fully into such a step. On step four of a natural turn or spin turn, it would be very easy for the man to collapse too early into his heel because the lady probably will not manage to project her body into a very full movement, so he can easily outmove her. In contast, starting with a nice full passing prep step, it's easy enough to create such a full body movement that it would be really hard to fall onto the heel too fast.