Haha I once abused this trigger in one of War3 RPG, it's called The Black Road, it uses the same trigger to prevent unit from entering that zone.
How did I abuse it ?
Simple, by using knockback spell that causes my unit to be thrown backwards while I was facing the other way around.
So when the system triggers, my direction + 180 = Entering the zone, very fun indeed
Luckily TBR creator only cover some small portion of the map with the region (only the entrance).
If they covered whole region with that system, my unit won't be able to move at all, constantly being pushed by the trigger