I agree on the surface this is very disturbing and to me what is the real question of expectations from RCL (Celebrity) by the passenger.
Stranding anybody on a small Island who is disabled by themselves is not right, period. It would have been better to have them taken off on a larger Island like St Maarten or like place and pre-arranged for a direct flight onwards with help by a support care person service by airlines and hotels till he got to his final destination.
My thinking is the cruise line does not offer disabled care service as a cabin service by a butler. I think the tour operator got it all wrong in providing the services he needed.
1) He went by himself without anybody to help if needed as his wife might have been that person or a friend. His monies would have been better spent instead of paying a single fare.
2) It sounds like the cabin was not meant for a wheelchair if it had a lip to move in. Did he request a disabled passengers accessibility cabin.
3) A butler on Celebrity does not provide service to move you or help in the washroom. Their is a not a care givers service. The communication went wrong as to the needs.
I have a friend who needs minor help in moving from a scooter or wheelchair and has canes. He will be on a cruise this year with his wife but they have arranged for a cruise scooter and a cabin designed for people with disabilities.
The mistake was traveling by ones self on a cruise ship expecting help to move about in your cabin, Had your wheelchair got stuck in a hall, they would help, had you fallen out , they would help or a passenger near by but in your cabin you must pay or provide a for someone to be with you not expect the cruise line to help as the staff are not trained for that service.
Could they have kept him on the ship, perhaps but depends on days left and what was going on in his cabin, If it was only the lip to the bathroom, might have provided a little ramp,
I think the issue is the support they gave him to ensure he got home safely and from a better location.
Expectation being by yourself of a ships butler , no , He or she is not your hired care servant as might be at home
My view /Rob
ps: I guess I was writing while Mike was also but I see we both make the same last point