Rha was clearly making a comparison of contrast between step four of the reverse, and step four of the wave.
There is no foot rise on the first step of a back locking action for either dancer, because rolling through the foot and up from the heel is necessary to generate a smooth rise that curves upwards in the vertical plane. You can create a crude imitation from the toe, and for students with very poor weight awareness this might be okay for a while. But the real action comes from moving the body weight through the foot.
Moving the body weight against the direction of travel - back to the toe - is never wise. When a foot is left via a toe drag, it occurs only after the body weight has left the foot. Wheras a heel toe release occurs while the foot is still weighted - it is not simply a heel drag, though that does subsequently occur in the follow through the of the pushing action of the toe release.
Even when moving forwards, where the weight lowers from toe to heel it never moves against the direction of travel in the foot in the way that you suggested, because the weight that is in the toe is only a small fraction of the body weight (the rest is briefly falling towards the point behind the toe where the heel will arrive). Force equivelent to the full body weight is exerted only only after the heel is down and the leg muscles start to absorb the fall of the body with pressure through the heel. Trying to absorb the full body weight into the toe is a common hangup - it has a limited role to support intermediates in slowing down and thus understanding the mechanism of how to divide the legs while up, but it must be discontinued before the step can be executed with smooth and unhesitating motion.