I guess the Judge who presides over the case will have to decide a number of things:
1) Having purchased the tickets, and therefore agreed to the airlines terms and conditions, does he then have any recourse to sue.
2) Is it discriminatory for the airline/handling agent/wheelchair company, to charge for the service provided - at the end of the day someone has to pay for it.
If Ryanair lose would they be in their rights to say they will no longer carry passengers who require such assistance.