I can't help but to wonder how would anyone be able to defend the existence of the FDS at this point
It’s not just about defending the FDS, but also defending “The Organization”
Two different entities that work for the same purpose and that require the same devotion and obedience. It about as crazy as the sign in the book of Revelation; where people worshiped the dragon because it gave the authority to the wild beast, and they worshiped the wild beast .
To tamper with the FDS is to tamper with the “Organization” of God. So they might not be able to defend the existence of the FDS with words, but they can defend it with the sword of execution, (disfellowshipping) which is carried out by the “executive” part of the Organization. No need to defend.