Willie: That is an informed explanation for a non-AB pilot. You may be correct, BUT.......
what would any pilot do, in any a/c, if it captured a false ILS Glide Slope and started descending. I hope there would be an instant disconnect and level off until the a/c was re-positioned to capture the correct GS. Whether a full GA would be necessary would depend on circumstances. A false GS was not uncommon at some airfields. The solution at every airfield was to have a gross error check ticking away in your mind. When it happened you were aware and knew what to do about it. On later versions of some a/c it became impossible to capture GP before LLZ. This helped the dummies who were asleep.
It has been known for decades that the approach phase is perhaps the most critical phase and during which most errors occur and incidents result; thus one would hope crews are at their most alert. After hours of safe sky underneath you most of it s now above you. Senses should be heightened.
If there is a known gotcha in the automatic system then surely the manufacturer should be taking steps to design it out AND publishing alerts to the crews. SOP's could be another level of avoidance. If Willie is correct this is a case in point; as too was the Korean B777 gotcha in San F.
Every a/c is trying to bite you in the backside. Don't let it.