billridesbikes

This is wrong, there is no unequal forces on some spokes and not others. For a rim brake under hard braking, say 400N applied by the brake shoes you have a rearward force of 200N pushing the rear of the rim and compressing it and an equal force pulling on the front of the rim. This causes all the spokes in the front half the wheel to be looser and the ones in the rear to tighten by the same amount (equal and opposite). As the rim passes through the caliber/contact patch there is a transition of spoke tension as the spokes pass through the point of contact and there is no change in spoke tension at these two points.

For a disk brake there is a torsional load that is dynamic. In this case the hub has to twist to act against the wheel rotation and brake disk. Because spokes are not rigid they can't transmit toque by acting like levers with x amount of force they can only loosen or tighten. And this is how they transmit the twisting motion of the hub. The spoke pattern and flange diameter determine how much the spoke tension changes. For cross-laced wheels exactly half of the spokes will become tighter under hub torque and the other half will loosen equally. This is why disk brake wheels are cross-laced.

All in all, the differences on the rim under different braking should be small, maybe about the same as the change in tension from tire pressure (?). But if I was a rim maker and I hadn't tested a given rim with disk brakes under heavy loading I would probably put a label to only use it with rim brakes to be safe. Why add additional risk to your company for a condition that hasn't been tested?