Who made the decision within the company? That's way more important than the fact the decision was made. Do they have a new position we were previously unaware of that handles requests for heads of state? What if the request is for the opposite? Who censors things explicitly? Who handles media relations? When? Why? Over what threshold do they consider it to be an issue?
I have no inside knowledge of Facebook's workings, but I speculate that the sequence of events was:
Employees saw this thread on Hacker News, posted on Facebook's meme network, the meme got a thousand upvotes, and someone did a one-off to reverse this decision.
Because it was obvious to everyone that it was the wrong decision. It was also probably obvious to everyone that the mistake that lead to this decision will keep happening.
Why?