Apple notified me this afternoon that they’ll be proactively refunding all purchases of Peace. It will probably take a few days to process.
As far as I know, this effectively never happens. When I decided to pull the app, I asked some Apple friends if this was even possible, and we all thought the same thing: iTunes billing works the way it works, period, and no special cases can be made.
This is the first time I've heard of Apple proactively refunding an app removed from sale. I wonder what will happen to purchase history in iTunes: will Peace be available for redownload from a user's account, or will it effectively disappear forever?
(In the meantime, I'm keeping Peace on my devices. It's still a great app.)