Make no mistake, this is a turning point for Lily's character - the realization of who she is, who her friends think she is, the decision to become something else - but no change is instananeous and no change is permanent.
I do have a certain paranoia of prison (I believe I've mentioned it before), and I think I always will, so long as TV dramas show me shivs and gangs, so long as "don't drop the soap" is a punchline, so long as the dominant narrative of our culture presents incarceration not as Us healing Ourselves but as Us punishing Them.
I do believe that subcontracting violence -whether to officials or to inmates- is still violent. If you're simply too timid or too physically weak to punch someone yourself, but you rely on others to dole out beatings on your behalf to maintain your lifestyle, you are no pacifist.
Speaking of pacifism, I kinda want to talk about the difference, in my mind, between pacifism and nonviolence. It's kinda similar to the difference between sexual purity and virginity - which is to say, one is a positive goal and the other is a negatively-defined technicality. Simply being nonviolent is easy. A potato is nonviolent, in much the same way that a potato is abstinent.
Well, most potatoes are nonviolent and abstinent. I suppose you could bean someone in the head with one, or use it to masturbate. I don't recommend either course of action.
...Where was I?
Ah yes, Lily's character.
I've said before that Lily's mindset is rooted in viewing humans as animals - and it makes sense, therefore, that control is her defining drive. If you found yourself on an island surrounded by gorillas, likely the first thing you'd do is limit their access to you, then find some way to train -which is to say, control- whichever of them seem most docile and useful. Lily's at the point where she has to realize this aspect of herself, to see it and name it and make the conscious choice to cede that control.