The issue is that if you have a bug where the feature isn't activated even if they pay, the user would lose money. It's natural that as you activate the feature

The issue is that if you have a bug where the feature isn't activated even if they pay, the user would lose money. It's natural that as you activate the feature you should acknowledge the purchase. Otherwise you could have bugs like double charging and such. It was an unfortunate mistake by the author, but it makes perfect sense why it happened. The person who made the mistake should lose out.