[That was a little surprising. Touma was still learning about this place, so the idea that someone couldn't leave or wouldn't want to seemed odd to him.]
Why can't they leave? [And the only reason he could see for wanting to stay was...] Are things really that bad back home that you'd prefer to live in a prison? [The country club atmosphere hasn't sunk in, yet. Touma could be too smart for his own good sometimes... absent-minded genius.]