Great catch. I re-read area 2-15 and realized it wasn't terribly clear.
Aborn is all about redundant measures. She wants Wildsgate no matter what, so there a few concurrent plots afoot. She is poisoning her brother, while seducing the captain, while prepping a coup.
Ideally, if any one of these fails, she can step in with another measure. (Even if all goes as planned, Sergio the Vizier and Sodersund the Regent are going to suspect something is afoot and challenge her claim to the throne.)
Tell your players that it was the writer's fault for the confusion.