It seems likely the purpose was to cause more people to think about the game Fortnite by virtue of the publicity from this.
It seem like something their lawyers pitched to them as “hey if it works, great, you save millions a year on the App Store percentage, and if it doesn’t, hey, at least you’ll get a whole lot of publicity, which should drive your sales up enough to more than compensate for the losses of being off the stores for a bit.”
The word you’re looking for by the way is “financially”. Fiscally is to do with taxes.