You are being too cynical. He's giving away stock not cash because if he sold the stock first to raise cash to donate, he'd have an enormous capital gains tax liability. By gifting stock, he can gift a far greater amount and the tax-exempt recipient charity can sell the stock itself to raise cash. This is standard in situations like this - e.g. it's what Buffett did when gifting away almost all of his billions.
Also the cause you listed is just one of many that he is gifting to so you're missing the forest for the trees. To help overcome this, list all of the good causes he mentioned (personalized learning, curing disease etc), then list the ones that you don't like. I bet the list of good causes will be far longer than the list of ones you don't like.
Mr. Zuckerberg and his wife, Dr. Priscilla Chan, said they were forming a new organization, the Chan Zuckerberg Initiative, to manage the money, through an unusual limited liability corporate structure. [...] By using a limited liability company instead of a nonprofit corporation or foundation, the Zuckerberg family will be able to go beyond making philanthropic grants. They will invest in companies, lobby for legislation and seek to influence public policy debates, which nonprofits are restricted from doing under tax laws. A spokeswoman for the family said that any profits from the investments would be plowed back into the Chan Zuckerberg Initiative for future projects.
Someone with more knowledge of the U.S. tax code than me will be able to explain how he's going to achieve this while funding a new corporation (perhaps he'll set up a foundation that owns a corporation, similar to what some endowment funds do to avoid UBTI), but there is no way that he's going to make this gift much smaller by doing it in a way that realizes a taxable gain at the time of gift.
Also the cause you listed is just one of many that he is gifting to so you're missing the forest for the trees. To help overcome this, list all of the good causes he mentioned (personalized learning, curing disease etc), then list the ones that you don't like. I bet the list of good causes will be far longer than the list of ones you don't like.