You worry too much.

There are a number of airplanes that anchor the shoulder harness that way. The shoulder harness' job is to keep your face from slamming into the instrument panel. That said, it will not guarantee that your face will not contact the instrument panel. If you impact so hard that your tail section deforms, when the tail is the last part of the airplane to the scene of the accident, your cockpit has already deformed in an manner that is likely not survivable. At lease in the most common accident situation which is a straight on impact. If you manage to have a landing accident that cartwheels the airplane, typically the wings and engine area take the most abuse. The tail section is pretty light and the mechanics of that sort of crash appear to involve more repeated impact of the heavier parts of the airplane (I hope I formulated that right).

So the shoulder harness mounting is intended to do its job in a survivable accident. Your job is to have an accident that stays within its design parameters.

Best of luck,

Wes
N78PS