It was dumb by the official, but somewhat understandable. He blew the whistle because the UTEP player possessed the ball. If the ball was beyond the line of scrimmage, then the play would be dead at that point, kind of like downing a punt. However, if the ball is still behind the LOS, even after a block, the kicking team can pick it up and advance it for a first down, which UTEP tried to do. After the official blew the whistle when the player grabbed the ball the play was dead though and by rule it had to be replayed.