I think it's fair. At first I was annoyed (even though I RNG lol) because I'd spent hours in DPP using the Pokeradar and learning how to do it wasn't easy either, but it's quite fair that GF give a few shinies out I think. I know if the RNG was never cracked I'd be beyond elated for this anyway! :P
I still think something like the Pokeradar might've been fairer though. I know it reduced it to a 1/40 chance or something but at least you had to work for it - not that completing the dex isnt work, but you can't AR your way to a 40 chain.
I already have a shiny haxorus but I will have to catch that one, knowing it's just sitting there waiting would kill me hahaha.