Bear,
Take it easy. This (mechanical) back-up law may be ultimately useful in case of electrical reconfiguration when the power switch from one source to another (something very transient, to begin with). As you say in about every post, the THS is powerful, and all FBW aircraft are fully certified to be flown with THS trim instead of elevator pitch control.
Design is based on FBW (electrical control), whatever you can say about that won't change this fact. Anyway, they have provided a mechanical back-up, just in case, in a very remote situation, it may be needed at one point for the pilot to use it.