Especially with the Rams only having 1 timeout left.
In either case they were going to have to stop them from getting a first down to have any chance. It didn't matter if it was at mid-field or on the Lions 20.
Going for it gives you one more chance to keep the drive going and possibly win the game.
Once you punt you put it all on the D to prevent a first down.
Why not get one more offensive play when field position didn't matter for the Lions at that point....they only needed to run out the clock.
