Hmm I still can't get my head around this...
Let's take the same aircraft, but with two different weight at the same altitude.
Let's put these 2 aircrafts at Vmd.
Glide range is the same, right? So from the same altitude we can all agree that we're descending along the same glide slope.
BUT the rules says that the heavier aircraft has a higher Vmd ie should cover the distance faster to reach the same point on the ground.
The aircraft descends quicker when it is heavier.
Which is the exact opposite of the statement in the question...
Am I missing something here?