After the exchange, you see Dawn's face and her eyes almost seem to be aware of all the cops behind her, watching her. She is in 100% self preservation mode and feels like she has to be "strong" or risk getting ganked by the other cops after this is all over, which is why she asks for Noah.
My problem with this is the concept is good, but how they handled it a bit weak. Her self preservation seemed to lead her to mostly just sit around worrying and whining to Beth. The cops that were causing issues (as presented by the show) had all but been taken care of. The last one was the dude in the exchange, I think. I don't think I even recognized the cops behind her in the exchange, and aside from the midget chick they didn't look very contrary. Instead of just making Dawn a passive, whining participant in her situation, they tried to make her active, by what, demanding Noah? Ooooh, that's really gonna show the haters. They could have easily had her man up, like she did with the dude that got tossed down the elevator, but this time where everyone can see, at the exchange, where she takes back one of the 'good' cops and then blasts the 'bad' cop. Of course, that only fits the situation they were writing toward, and not the way they will have an end-goal and have to twist the writing to meet that. The show seems to have a lot of if statements, like if Beth needs to die and if Dawn is afraid she's losing power, but can never really write that into a coherent then statement, like then Beth stabs dawn in the shoulder with scissors and Dawn blows her head off.
Especially because they set it up that Dawn asking for Noah probably wouldn't even impress the 'bad' cops she was trying to protect herself against (that all seemed done for anyhow). The general implication seemed to me to be that she was weak because she had her little personal assistants and wasn't even raping them or anything, but actually cared for them. How asking for Noah would have made her look strong in reality, or Dawn's own mind, is beyond me. Had she demonstrated something a bit stronger than the 'he'll be back, they always come back' shit then maybe I buy it.
The better setup is the crew offers Dawn's two cops, but she says she'll only take the 'good' one back, and wants Noah instead so it's a fair trade. After all the mentioning that Dawn would negotiate if Rick's crew could help her out of her situation of losing power to the 'bad' cops, and they build that up for what? Nothing. Because this show has trouble putting together coherent if-then statements, and instead comes up with hella-melo-dramatic end results after they've already written themselves in one direction, and just let it go figuring their viewers don't care anyhow as long as zombies get killed and Daryl looks dreamy emoing it up. Keeps me watching, at least!