This is strange, if hackers actually wanted to donate those money, they would have kept it secret. It's clear that they had some ulterior motive - maybe they wanted to boost their own reputation or maybe they wanted to harm Bitcoin's reputation, or maybe the charities were the actual target?
We really don't know what is their agenda for doing that and for posting that donations over the net for sure the only thing they want is to be known. Since if they got reputation about this for sure they can use it for extortion or maybe on illegal things that we can't imagine.
But we really don't know the on point reason about this so expect more talks about those happenings will continue to flow.