Hypersmurf
Moderatarrrrh...
This is correct. The rule variant is on page 69 of Sword and Fist, under "Double-Handed Disarm." It applies to anyone fighting unarmed, and it says nothing about being able to grab the weapon instead of it dropping to the ground.
It doesn't have to - that part is in the PHB.
p137, Disarm : "If you attempted the Disarm action unarmed, you now have the weapon. Otherwise it's on the ground at the defender's feet."
-Hyp.