I don't see anything outright that answers this question, as Passive Sensors requires an action be taken during the activation phase that allows a later action to be taken during engagement (although meaning you get no tokens during the activation phase).

Theory-crafting answer, maybe I'd say:

• When the attitude is 'defensive' or 'balanced', take the action as indicated by the dice rolled
• When the attitude is 'offensive', instead trigger the passive sensors

Thoughts?

For practicality sake, I'd let a Passive Sensors ship do it whenever they'd take a Lock, mostly. So it'd seem pretty high up in Offensive attitude (#1.5 I'd say), and not on the chart for Defensive/Balanced.

However, I'd probably let a non-offensive ship do it (at least Balanced ones), if it "looks safe" with most ships pointing in other directions. That's one thing I like about the Solo rules is that it leaves a good deal to the judgement of the players. It's not a system for robots.

When that ship engages, if offensive, follow the standard rules for a Lock action (nearest ship in special weapon arc, then nearest ship in arc, then nearest ship). If defensive attitude and if there are attackers who will shoot later... I think it'd be Calculate for defense.