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.
... But: our visibility of "what he's doing" probably isn't very good, so our estimates of "why he's doing it" may actually factor into our guesses about what will actually end up being done with the money. (E.g., if what he mostly cares about is looking good for giving away a lot of money, he doesn't have much incentive to make sure it really does have good effects. On the other hand, if he cares about looking good for saving lots of lives, he has the incentive.) So to that extent the critics may have a point.
Here's some less optimistic articles.
I remark that the last one is from the Daily Mail. If the Mail printed a story saying that the sky is blue, I'd look out the window to check it hadn't actually turned green. (The Atlantic has a better reputation. I know nothing at all about the Irish Examiner.)
Effective Altruists & Consequentalists tend to be vain with plausible deniability, always making a show of their set of beliefs, coming into the room loudly and attracting attention always repeating "effectiveness" "consequences". It gets annoying. I wish some would have taste.
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 :)