You can make immature choices and still be a good person. So I've always considered the CHICK/DIK scale less as a morality scale and more of a maturity scale. CHICK involves more mature decisions, consideration, thoughtfulness, respectfulness while the DIK choices are less mature and more brash. At least that's the way I see it.
I think that final Zoey decision encompassed that pretty well. Zoey decided to be the bigger person and defuse Emma even though she went full psycho. I don't think that made her a doormat. I think it was the opposite.
Besides, I think DPC anticipated that people would want things to be kept simple with shaping Zoey. You can tell that shit by the people who want to sKiP ThE FeMaLe PrOtaGoNiSt and complain about how you can't skip it right away (without realizing you can skip it after at least one playthrough). So even if it were 10 decisions that define her as CHICK or DIK, it doesn't really matter. People skipping the interlude will pick the same options for Zoey every time to make her either CHICK or DIK, so why not keep that shit simple. One major choice is fine by me for a skippable interlude.