I'm a happy multishipper for this game (though my preference for Balthier is putting him with Ashe because they're a mess that can never work long term and I love me some broken edges), but I always read them as rock-solid forever friends and partners, who perhaps might bang once in a while if they felt like it, but it was always less important than pirating together, and while I hadn't defined Balthier's immaturity in my own mind, I think that was an underlying reason, and I'm glad you called it out here.