If it was 4th down, the game is over anyway. It is sort of a loop hole to save a down if you were going to spike the ball anyway.
Just say there are 30 secs left, and it's 2nd down, you gain 7 yards. You can quickly go up and spike it, stop the clock, and give yourself another shot. Around 20 secs left, balled spiked on 3rd down, now 4th and 3 but the clock is stopped. OR player gets hurt on the 2nd down play, 10-second runoff, now only 3rd and 3 with 20 secs left.
Utlimately this could be applied to any down or distance when you have a chance to spike the ball. If you watch that play sequence over, GB basically got a free timeout for 10 seconds without wasting a down for a spike, which they were going to do without the injury.