Certainly this was badly handled by the carriers - who may have been overworked and unprepared for the woman's unusual circumstances. But ...
The woman is likely to be in her mid/late 30s and will have become (wearily) used to the difficulties in the use of public transport. I am glad that cabin crew have stated their willingness to help all pax but it is not just once they are aboard. If the woman is using an electric wheelchair to get to the Gate, what happens if there is a Fire Evacuation before she reaches there? So I expect that the Airport Management would be concerned for her too.
If this woman has ever travelled by air before, then she would know that there are aspects of her circumstances that the carrier must know in advance. If she has never travelled by air before, then, given her age and experience, she would know that her circumstances might need to be advised to the carrier. If you are buying a trip across the Atlantic, you would want it go smoothly wouldn't you? So let everyone know of your needs.
To me, this sounds like she has a grievance but not one that requires the intervention of the courts. If she wins, she will probably ensure that carriers will change the Ts&Cs for ALL disabled pax and that any change will not be in the pax's favour. Remember that any carrier (private or public) has a right to deny carriage.
Very sorry to hear about this case that should never have got this far.