Earlier quoted context omitted.
People with immense wealth (Gates, Buffet, ...) are great at coming up with innovative tax schemes to tax anything other than wealth.
Actually, Buffet's idea for quite a while has been that he and the other billionaires should be taxed more. It may be just PR, but that's a different goalpost.
Buffett's plan calls for a lot of other wealthy people to be taxed, but I don't see him doing a taxable transaction on his main holdings, I believe the effect on himself would be minuscule.