I think Jack was still a live ball carrier (and it was a fumble, Peter King's non-sense about hand over the ball notwithstanding) but down by contact rules are a get out of jail free card for refs who blow the whistle early. They've gotten much better in recent years about this, but its never perfect.

Of all the bad calls and bad rules interpretations these days, down by contact I can live with if its with a whistle.