[mindslight]

Exactly. It's not some hack that magically makes income tax liability just disappear, as many commenters are thinking it could be. Rather there are marginal tax benefits combined with strong asset protection, that make sense when you've got an obscene amount of money to manage so the administrative overhead becomes negligible - the question goes from "why" to "why not".

Another thing people are missing is that it's not an income tax dodge, but rather an estate tax dodge. The money will remain in control of his heirs, assuring they'll never go hungry or want for a place in the world.

It also creates more opportunities to play with asset valuations to evade taxes (eg separate the financial and voting interest of some stock in a closely held company, then claim the financial interest is worth very little without the control interest). But it's impossible to know if this is actually being done without seeing tax filings, including his (eventual) estate tax filing.