Questions can be raised about some of his specific donations, but when someone gives away $8B of his wealth, spending nearly none on himself, does it globally, influences other billionaires to do the same, picking at any one of his specific donations seems counter productive.
Yes Cornell is an Ivy League school, but it is where he went to school, he probably has very strong ties to that school, perhaps met his wife there, or his business partner, if he chooses to give back to that school that is also good.
Plus there was a tremendous amount he gifted to "education" so without knowing all of the details, hard to imagine that he didn't provide some sort investment in to under represented communities. If he helped Vietnam with their healthcare he obviously wasn't just US centric but helped where he though his donation could have an outsized return.
By the way he gifted a large amount of money to the Obamacare campaign, so by proxy, he was providing healthcare to his workers, and more likely than not.