I'm not a 320 armorer, and definitely not @HCM, but I had this same question in my head a while back. In case it helps, I found this very good 320 disassembly video below useful in understanding the motion of the trigger bar in the context of this thread. When the trigger shoe moves backward i.e. in a normal press, the trigger bar moves forward. So if you dropped a 320 on it rear, inertia is not going to result in the trigger bar moving, since it is against it's normal travel. This is my understanding why a tabbed trigger shoe on the 320 would not have any benefit, at all.
The movement of the trigger bar / trigger shoe is is shown starting around 30 seconds into the video, as he removes the trigger shoe from the FCU.