One of the most interesting parts of this is the choice to make Holdfast a C4. They really wanted to make this a political organization, and were willing to forgo a staggering amount of tax savings - in fact, $17m in tax donating away a $3b asset. Probably the least effective estate planning from a raw $ perspective in history.
Major props to the family for doing this - this is now the definition of "putting your money where your mouth is", and I hope this model is a success and serves as a template for others to follow.