I am so sorry to hear that. This is a case where an
avian vet could have made a big difference. I suspect a vet was used that was clueless with respect to birds. The bird could easily have been saved. The egg binding was under control and an experienced vet would have had no troubles with that bird.
Again, a guess, but this is the time to point out that if you have birds, you must have an experienced avian vet. The "dog and cat" vet is not enough.
I am so sorry about this outcome for this bird.
Foer folks thinking about living with larger birds, this is one reason you shouldn't!
Again, a guess, but here is the likely scenario and I've heard it a hundred times. The cost of saving the bird was more than the person wanted to pay. What's the cheapest alternative, you might ask? Put the bird down.
I may be way off base, but I doubt it.
Bill