I have to think that Delta's going to paying something here. The problem will be that they weren't able to clearly identify when/if she met qualifications to fly. They had her on the first flight before deciding she couldn't stay on it, and then sent her to another airport that didn't have a way to meet her needs. That will get them. Plus, their travel agent alerted Delta to her condition when buying the ticket.
On the flip side, the UK article shows she only had one leg as well. So not only did they have to get her on the plane, they had to do it with a wheel chair and figure out how to get her from the wheelchair to the seat. Not fun. Delta should have turned her away from the start, if they couldn't figure out how to accomindate her.