Asmodia never let herself think out loud, at all, that she didn't actually want to go to Hell. It isn't necessarily a disloyal thought, if you don't try to escape, if you truly believe that escape is futile; but the part of Asmodia that wordlessly and silently decided which thoughts were safe to think, was afraid she might not think that. It didn't seem urgent, to that silent buried part of her. She wasn't expecting to end up irrevocably damned this soon.
Once you sell your soul you don't have to pass loyalty tests the same way, because escape really is futile, then.
Once she sells her soul, they probably won't execute her for what she thought just before then - they probably won't execute her for thinking, just before this, about how she might not want to go to Hell -
Thinking just once in her lifetime to see if escape is possible, even though she's already inside this locked room with security around it, and they wouldn't have brought her to this villa if they hadn't verified her as Lawful Evil, which means that even if there were some way to kill herself and they didn't raise her she'd just end up in Hell -
She doesn't sweat on the outside, while she pretends to be reading her contract very carefully. She's thinking it, she's finally thinking it, now that it's too late, but there isn't enough hope in her, really, for her to sweat. They're probably reading her mind, right now, and she's probably losing points, but not so many points that they won't just let her sign and let Hell take good care of her later, for her current sins.