It's fiction. All adoptions are not alike, all adoptees do not experience the same feelings, there is no way possible to portray an adoption story that would be to everyone's liking.
I haven't seen the movie yet, but the article says it is distressing that the child was rejected by over 100 potential parents. Are they trying to say this is some kind of outrageous, unthinkable, never-in-a-million-years would happen scenario? I think they need to be removing those rose colored glasses. That kind of thing really happens, pretending it doesn't does not make the world a better place, just a more ignorant one.
Perhaps it would be insensitive to show the movie to a group of older children who are still hoping for the right family to come along, as it would hit too close to home, but I don't think Disney did anything wrong by portraying this in the movie.
Is "Cinderella" boycotted among stepfamilies?