Easy. Abilities default to play, so her ability can be read as "After battle, capture this character in play to an opponent's land of bondage". If she's not in play, there's no capture.
Abilities defaulting to play is not what's in question here. The fact is, SW does
not say what you suggested, and she
was in play to be targeted for a pending trigger. Anecdotally you think Archers work with an implied "in play," and anecdotally I do not so that's moot. I vaguely recall someone asking me for an example of how we still haven't nailed down how triggers and delayed abilities work; this is the perfect example. All we need is a top-down rule: is the validity of a target determined when it is targeted, when the targeting ability executes, or both?