Because societally we want to encourage the act of giving anonymously with a big reveal in the twilight years? Doesn't sound that hard to understand.

Sorry, I guess i interpreted anonymous donation as a Truly Morally Selfless act, and the fact that we're talking about it now would be some weird flex.

But sure, if you put out a call for solicitiations when you announced you were giving it all away, you probably also need a big announcement when you're done or you'll be dealing with development officers all day every day.

Well, sure, anonymous donation is that. Then we want to encourage that so we find anonymous donors, deanonymize them, and canonize them. That makes more people want to be anonymous donors, a thing we want.