Tidus probably could have gone inside, but he's chosen to wait standby. If the groups really get into trouble, they might need some emergency backup---and he's got the skillset for that. For now, though, he's content to check his equipment, pausing to smile when he spots Sora and his moogle. They match so well...unlike him and Zunne, who refutes such silliness.

"Hey, Sora! So you're the backup too?"