Zuckerberg's use of an LLC for giving away his fortune--what good is it?

Mark Zuckerberg has announced he is setting up an LLC as a way to give away 99% of his fortune, which consists mainly of Facebook stock. I was puzzled by this at first, because doing it this way has no tax advantages. The LLC is a for-profit enterprise, so (a) he gets no deduction for giving away his stock, (b) if the LLC sells the stock, Zuckerberg pays the capital gains (it must be the basis is *not* stepped up to the time of donation, since that would be too good as a tax dodge), and (c) Zuckerberg needs to pay tax on the LLC income.

What I think is going on is that this is a personal accounting device, like having a separate bank account for charitable giving. The LLC will donate the stock to charities and never earn capital gains. The stock pays no dividends, so it has no income. And Zuckerberg is retaining enough stock that he can give away directly that he will hit the 50% limit on donation deductions each year anyway, so he can't use the stock donations for deductions in any case.

Anybody know if this is correct?