Think of it this way: If it were a sideline, instead of the goal line, would this be a catch?
No, it wouldn't. The same concept applies to catch/possession in the EZ - it has to be established prior to any progress being granted. You can't have a valid catch or possession since while he's in the air, possession/catch isn't finalized until he returns to Earth, and where he hits the planet (IB/OOB) determines catch/possession.