Xehanort is not inclined to trying to feel happy and content while imprisoned and being forced to watch people get terrorized, for some reason. Maybe there's something in the air, like that forced oppressive unease from the other rooms, making Tidus react to all of this so utterly calmly and acceptingly. Their captors did want cooperation, and clearly they're getting it from some sectors!

Maybe it's the food. Said 'food', such as it is, is eyed dubiously from his safe distance. Going a week was going to be very tough even for him.. "Given it's blocking all other forms of magic," is the sullen response, "And it's already proven they can make us feel what they want, that really can't logically be trusted either."

Tidus might be terminally inclined towards helpfulness, but there was a good chance everyone else wasn't. He could hope. "I'm sorry, Tidus. I'm not as.. naturally inclined to trust as you are, I suppose. Especially with so many bright red flashing warnings flying around that the train has been helpfully introducing us to over and over and over. This isn't okay, this isn't fun, and in spite of what happens in the future I do not yet enjoy watching people run around in terror."