Halting the advancement that would've ordinarily happened is not "ignoring it", it's doing something to actively counter it. That "something" ends up canceling the previous trajectory to evaluate to "nothing", but that doesn't happen through ignorance - it required a countering action.
Example: You're driving your car when pedestrians appear in front of you. What does "ignoring" them constitute? Stopping the car, or running into them at the previous speed?
Example: You're driving your car when pedestrians appear in front of you. What does "ignoring" them constitute? Stopping the car, or running into them at the previous speed?