Now, I don't have the Bassa magazine infront of me so can't quote exactly, but I'm sure that the arrangement was NOT that CSDs should have the same rooms as flight crew.
The arrangement was that CSDs should have the same standard of rooms as FIRST OFFICERS..... It's normal that the Captain is given a higher standard of room than the rest of the crew - CSD included.
Another part of the story that must be looked at is WHO arranged for the upgraded room.
If British Airways pays £100.00 for a Captain's room, £75.00 for a First Officer's room, £75.00 for a CSD's room and £65.00 for the rest of the rooms, that's surely all the Unions should be worrying out.
It's surely up to each individual hotel if who they choose to upgrade. So long as the company aren't booking a different grade of room for the CSD vs. First Officer, it should be of no consequence what kind of room anyone actually occupies.