I don't see this as being the least bit childish.
I think it is well thought out, well designed, and has as much chance of provoking thought on important issues as anything else, and far more chance than doing nothing but wishing. I do think that they need to be seen by more than the money-counters, though.
This doesn't just make the statement that "we" are here and aren't going to contribute to their cause--it tells them WHY. Seeing something like this when I was a JW might have scared me and put up my anti-apostate shield, but I can guarantee that it would also have made me WONDER and THINK, even in small increments that slowly grew. I would have had to check into it sooner or later.
Surely there are others there now like I was then--on the inside looking out, filled with doubts and questions but with nowhere to turn for answers and more information.
It's worth a shot.
~Merry