It sounds like you handled it fine. This feels like it sort of falls in between Coerce (Using the threat of the mitflit's boss. Your boss sent us, so you need to do X, or else the boss will be mad.) and the player attempting to Make an Impression. Generally speaking each of those take a minute to accomplish, so are hard to do in combat. So it would very much be a GM decision. Another option would to have the Mitflit flee for a round or even attempt to run back to the boss to check (which could bring reinforcements). But with all that said, you rewarded the player's idea and critical success, even if it isn't exactly what the player was hoping for. So, well done!