Yep, this is a bug. What kind of bug? AI.
If you have a six-point lead, the defense has no timeouts left, and you have the ball in their end of the field, you should
a) kneel down and run as much time off the clock as you can, kicking a FG only if you have to;
b) run the ball up the middle, staying in bounds, but otherwise doing a); or
c) do this.
That's right. I score the game-winning TD. Thanks, AI!