Theory doesn't make any sense, if he wanted to transfer assets to his children, he'll just do that directly rather than start a foundation that has disbursed $66 billion in grants [1].

Note that I'm not saying Gates is a good guy and doesn't use his foundation to exert influence. But, saying he started a foundation to transfer assets while dodging estate tax reeks of "they just write it off...". Wouldn't he have been better off handing over that $66 billion to his children and paying 18% to 40% as taxes?

1- https://www.gatesfoundation.org/about/foundation-fact-sheet