By "negative action" I mean that he can suppress content he doesn't want people to see.
He can also plaster Facebook with his face, in a more or less subtle way by tweaking the newsfeed algorithm, but ultimately if he wants to gain positive reputation, he needs some really newsworthy and moving thing about himself to happen, not just "7 awesome facts about Mark Zuckerberg" clickbait trash.
Reputation isn't just a zero sum game.
It's a bit surprising that anyone is arguing over this issue. Clearly if Zuckerberg can convince people that he is giving 99% of his fortune to (worthy) charity, it will enhance his reputation and status. This is obvious to anyone, and therefore it opens up the reasonable possibility that his primary motivation is in fact to enhance his reputation and status.
Maybe the problem is that people are getting hung up on the word "publicity." When people say "He's doing it for the publicity," the charitable interpretation is "he is doing it to enhance his reputation and status."
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 :)