As far as I understand, he wouldn't avoid estate taxes. Whoever dies last would still own the LLC as an asset and the estate is taxed on the value of that asset. With their combined estate tax exemption, about $10.5 million, any value over that would be taxed at 40%. Unless he remains true to his word and he expects to spend it all before he dies.
The only "avoidance" of taxes happening here is during the initial transaction of transferring the Facebook shares to the LLC's ownership. Of course as the LLC sells shares that have gained value, the capital gain would be taxed, as would any dividends or growth from any other investments the LLC makes.
The only "avoidance" of taxes happening here is during the initial transaction of transferring the Facebook shares to the LLC's ownership. Of course as the LLC sells shares that have gained value, the capital gain would be taxed, as would any dividends or growth from any other investments the LLC makes.