Parro thinks Sabrina's "white knight" thing is a mask, because anyone so successful must have an underlying agenda and strategy consistent with the brutal realities of magical girl life.
As of the end of the update, Parro has clearly updated her estimate of Sabrina from "someone who is just as selfish as I am" to "useless idiot without the guts to kill me". As evidenced by the fact that she feels safe enough to laugh in our face.
That's also why she has no problem telling us she intends to escape and unleash horrible vengeance against us, by the by. It's not hypocritical on her part. It's not even some ill-thought-out counterproductive attempt to persuade us that the world is ruled by the law of the jungle. We can't legalistically point out that if we followed her standard, she would be dead, because she already knows that we don't follow her standard, and she doesn't give a flying fuck about legalistic standards in the first place.
Parro knows that we're not like her, and she's throwing it back in our face as a power play of her own: either we go back on our word and punish or kill her for being an insufferable brat and a material threat to our power bloc, or we have to follow our high-minded ideals and sit calmly through her backtalk as she calls us spineless soyboy leftist beta cucks.
Parro is still treating this conversation as a power struggle, and actually caring about rhetorical one-upsmanship at this juncture will only make it clear to her
and our allies that she's successfully struck her target and made us feel insecure. Wanting to win a verbal spar with someone who doesn't care about the consistency of the words that are coming out of her mouth is pathetic in the first place.
We don't actually have to get the last word here. These girls can feel smug all the way through to their regular community-assigned check-ins with trained parole officers.
Way to get through to her, loosen up that shell of "hard decisions," is to drop the "mask" but thereby reveal something even more alien and impossible underneath it.
Your suggestion to flex our powers as we leave is nonsubstantive on that front. Parro is a lichbombed magical girl, so she implicitly understands that her captors will have weird powers born of arbitrary wishes and can send disposable bodies to talk to her.
Flexing our powers only looks like something she understands: a naked power play to soothe a bruised ego of our own.
