A very intriguing premise, and some good dialogue here, catching the characters' mannerisms well! You might ponder a little more the reactions of the characters to the choices offered. Yuna has strong feelings for Tidus, and Kimahri too in a very different way. Auron knows very well that Tidus would be following his father's path -- a futile path. I think there would be some animated discussion, even if they all agreed that the Final Aeon was the only option. (Also I recall that in game, Lulu was the first to offer, followed by Wakka, another fun scrap to play with.) These are just general observations, ways you might play with and deepen this idea a little more: it's a great question to ask!