Is it at all clear that Zuckerberg is getting any tax benefit from moving his shares? I believe the "foundation", which is not a non-profit, will still pay taxes when it sells FB shares. If the LLC donates to a non-profit then it will get a tax benefit.
IANAL, so please someone who is actually informed feel free to correct me. A lot of what I've seen written is completely un-nuanced and probably wrong.