There could be a number of reasons why ex-witnesses don't get involved. I expect that many don't even know of this place as they were too scared to look while they were still in. And being disfellowshiped on the common grounds of porniea, most probably just carry in their new life knowing that they will go back. Some I expect still want to return to the congregation, family and friends .. and are thus still 'believers'. Overcome by depression or physical tiredness, people might just not have the energy to do anything of importance at all. And others like Ray Franz, were or are, waiting for the Organization to reform before making their move. How many leave the Society without being pushed, because of their own conscience may actually be a quite small percentage too.
So perhaps the thousand or so members here, should be expected.
Yet I am convinced, we the few, who take to time to make meaning posts, hit above our weight in helping those who dare to look in through the window. And I'm sure that despite the fact the we may be viewed as complainers and malcontents, the Governing Body knows we exist and we are a pain in their side.