He had meant even for the bunk rooms, but Romeo not being allowed in a two-person room? Tidus can get why, but-

"We should change that too! Tell the train it should get in beds that can be split in two, so friends can share a room together too! You've been here a long time - you should get a nice room too! Something more permanent."

Oh, Tidus's mind is thinking! "Have the rooms like we do now... but make the beds like the ones you can put together or split up. And you don't get kicked out if another person leaves, so you can get a new roommate. But maybe you have to get a new roommate soon, so it's fair."

So someone isn't hogging a double room forever.