The mixup is a little more complicated than that. When you push ABC, the game registers it basically as a throw break since you're hitting B and C. Any time you hit B+C the game thinks you're doing a throw break, it counts it as one. So if the opponent grabs you RIGHT AFTER you do that, then you end up getting counter thrown.
So at first they can just go for a normal throw mixup, but if you start throwing barrier into it, they just bait out the barrier and then throw you, forcing a new mixup. And they can just play with your reactions by making you think a throw is coming when it's not. To avoid this you would have to do a simple throw tech instead of barrier.