>>10073125>>10073259>>Drosselmeyer reveled in other people's despair. He wrote his stories such that everyone in them suffered as much as possible because that made him happy. I fail to see how Fakir writing a mutually beneficial end for him and Ahiru would put him on the same level as Drosselmeyer.
You basically answered yourself. What Drosselmeyer did was bend reality to his needs. Fakir changing Ahiru WOULD BE THE SAME FUCKING THING. Ahiru is a duck who only turned human to save Mytho but she supposed to have confessed her love and disappear. She overcame that tragic end by saving Mytho by restoring his heart, which cost her only way to be human (that was though his heart's shard).
Fakir had to stop Drosselmeyer's meddling with reality and restore it to what it was (you even noticed that the furries changed back into animals aka the Cat Dance Teacher became a actual cat). Ahiru as a duck was her REAL form. If Fakir wrote in that Ahiru can be human again, he's bending reality to his means, meaning he's no different from Drosselmeyer.