It's more than the NDA. ALL GA's have lots of children and that is all leverage that the church uses to keep everyone in check. Imagine the level of shame that everyone would endure if a GA came out for the truth. It would be devastating to give up the free college for the kids but then to put them through the shunning too?
So, to speak out against the church means that you would loose everything financially and your entire family would have a lot of shame to deal with.
I wonder if a GA came up with a plan...like hiding a lot of wealth overseas and setting up a new household in a country that the church can't get its hooks into. All of the extended family members would have to be on board as well.