I see people trying to equate NFL rules to NCAA rules which isn't correct.
Here is the NCAA rule:
Catch, Interception, Recovery
ARTICLE 7. a. To catch a ball means that a player:
1. Gains possession of a live ball in flight; or
2. Leaves his feet and firmly grasps a live ball in flight, the ball first
touching the ground inbounds while still in his firm grasp; or
3. Leaves his feet, firmly grasps a live ball in flight and either first
returns to the ground inbounds with any part of his body or is so held
that the dead-ball provisions of Rule 4-1-3-p apply (A.R. 2-2-7-I-V and
If one foot first lands inbounds and the receiver has possession and
control of the ball, it is a catch even though a subsequent step or fall takes
the receiver out of bounds (A.R. 7-3-6-XVII). A player who satisfies any of
these three conditions is said to have completed a catch.
b. An interception is a catch of an opponent’s pass or fumble.
c. A catch by any kneeling or prone inbounds player is a completion or
interception (Rules 7-3-6 and 7).
d. A player recovers a ball if he fulfills any of the three criteria for catching
a ball that is still alive after hitting the ground.
e. Loss of ball simultaneous to returning to the ground is not a catch,
interception or recovery.
f. When in question, the catch, recovery or interception is not completed.
Basically, all you have to do is hit the ground with the ball in your hands. What happens after is irrelevant, as the play is dead. Moe wasn't going to get three extra yards if he had hit the ground and slid forward.