Daisy has their frequency locked in, she would have to be dealt with first.Going to be interesting to see how they stretch this to 4 episodes. I mean, if Izel can just make shrikes and send them out, why does she not just infect 99% of Earth, and game-over? Not really a subtle bad-guy.
I have to say, the explanation for Sarge they went with is a good use of established continuity although, once again, I wish there was a bit more related to the comics this season.