Rear caliper service and pad change

[Grumpy Goat]

From what I understand (and experience) the minute you press the rear brake pedal the brakes are no longer linked.

Where did you read that?

This link describes the overall operation but does not actually say that the brakes are decoupled once the rear brake is pressed, but the effect is the same. This WebBike World article also explains the partially integral brakes.

When the right handlebar lever is applied and the front brake is applied, the computer decides the proportion of braking effort to apply to the rear brake to ensure that braking is effective and there is no lockup. When you press the foot brake that proportioning is overridden, and the braking effect at either wheel is based on the amount of pressure on each lever, independently.