Effective altruists care.
Effective altruists care about effectiveness. If the claim we're assessing is "Zuckerberg is only pretending that this money will be used to do good; actually it's a pure tax-avoidance scam and it'll all end up being spent on his family" then sure, effective altruists care. But if it's "Zuckerberg really is putting all this money into trying to improve the world, but his motive for doing so is that he wants to look good" then no, effective altruists shouldn't care why he's doing it, only what he's doing.
... B...
Mark Zuckerberg annouced that he is going to give away 99% of his facebook wealth ($45 billion) over his lifetime.
He announced guiding questions:
It's interesting that "live much longer and healthier lives" is on the list. Larry Page seems to divert money inside Google into Calico for anti-aging tech. Under Cook Apple also invests into health.
The future seems looking good :)