I think it was meant for situations where the receiver went up for the ball, landed, and then got hit and lost the ball. He got two feet down and held on to the ball momentarily. So is it a catch and fumble, or incomplete?
The rule seems to be saying that merely holding the ball and putting two feet (or the equivalent) down isn't enough. You have to come down with the ball and do something with it before it is a catch.
It is what "do something" means that is in question. Clearly, the "football sense" of nearly all who have commented on the play is that getting up off the turf to try to advance the ball is "doing something."
If the rulebook says otherwise, it should be changed. If the rulebook is unclear, it should be clarified.
SD
"A forward pass is complete when a receiver clearly possesses the pass and touches the ground with both feet inbounds while in possession of the ball. If a receiver would have landed inbounds with both feet but is carried or pushed out of bounds while maintaining possession of the ball, pass is complete at the out-of-bounds spot."