It's not an invalid worry. Soldat still has trigger words. It's entirely possible someone could influence them, control them. So they can't brush off the idea that someone could maybe reach through her magic to influence her, too.

They're quiet a moment, disappearing into the storage car for the fixings for an egg-and-cheese sandwich. Quick and filling and, above all, comforting. On their way back in, they have an answer: "I think not wanting to be is important. You magic works because of how you feel. That's what you said. And that's part of how you feel."