I think he's talking about AEB engaging on the car you're trying to pass. If you are overtaking on a 2-lane you want to back up, wait for your opportunity and close on the vehicle to be overtaken at a decent rate of speed before pulling into the other lane in order to minimize time in the wrong lane. Also if the other person decides to be a dick and try and prevent you from passing this gives them less of an opportunity to do that.

If AEB forced me to get in the other lane before stepping on it because it thought I was gonna rear end the car about to be passed I would be very annoyed.