While this may have been an "internal company matter" initially, it did eventually become very public. There has already been a huge amount of speculation out in the open regarding whatever might have happened in this case, much of it quite negative.
So given all of this speculation and gossip, it's not at all surprising that there are people, including users and customers of GitHub, who just want some facts. And there's nothing unreasonable about them requesting such information, especially when it's paying customers doing the asking.