She was too fat to be strapped in with a seatbelt, so she was denied the ability to fly back to the US (I do wonder why she had to die and couldn't find a doctor in Hungary, but that's for another day). What I'm wondering is why the airline refused to ler her stay in her seat. Did it really just care that much about people being strapped in? Or was this caused by government regulation? Thoughts? More precisely, facts?
It sounds like she did not give the airline advance notice that she had special needs. It definitely was not a round trip fare as far as the article states. Between the lift needed to get her IN, and the seatbelt extension etc. needed once she was in, it sounds like the kind of thing you can't make a last minute reservation for.
Even oxygen patients who are perfectly mobile have to call in advance to be sure they will be admitted on the plane.
it is probably an FAA regulation, though I couldn't cite it to you exactly. Without regulations, I would assume that the airline might have let her sign a waiver to remove liability if was injured because of a lack of a seatbelt, but this is speculative and they may opt to continue their policy.
Unbuckled persons can be dangerous not only to themselves, so the airline might be not willing to accept her even with a waiver signed.