In a way, I think that makes the reveal all the more devastating to David. Because yeah, since this season is so long after the first one and we haven't seen Amy in awhile, you don't really expect her to factor into this. I wasn't even sure that was Katie Aselton at first. It doesn't fit that pattern that we as humans seek, if I can pull from Jon Hamm's words.
So with the reveal that Amy is living in seclusion and that Farouk is targeting her, at least to me, was a surprise. And all the more tragic to David when he realizes that his sister is gone. Worse than that, Lenny of all people is in her place. And now part of me wonders if Farouk picked Amy of all people just to get under David's skin, knowing it would enrage him.