Balthier would prefer to send them to basecamp because the idea of someone finding him and sending him home (childhood home, not world home) is a nightmare. That said, he doesn't LOVE losing two people, so could be convinced to (2) bring them along if the Thessyx seemed ammenable.

Sidebar: Balthier does have his two-seat hovercraft he can bring (and would volunteer it ahead of time). He's the only one who can drive it, but it could be used to carry supplies, injured people, or ancient Thessyx.