Well, I didn't actually say "absorb" but if the screw flexes at all, then it does actually dissipate energy. In fact anything in the system that flexes, stretches, or heats up is dissipating energy. I did simplify the system a little I guess. More energy dissipaters: Knots tightening, harnesses stretching, climber's beer gut sloshing around, crampon catching on ice and shattering ankle, rope whipping through carabiners, rope slipping through belay device and belayer's gloves, belayer sinking onto anchors, cordalette stretching, pins shifting in manky rock, etc.
The point is if there's a screamer in the system and it activates at all, it will reduce the energy, and therefore the shock loading, imparted to the pro. Yeah, 9% maybe isn't a whole lot, but like you say it could make the difference...