The first two sentences there has a nuance that most humans never differentiate, and is actually the core principle of all ethics debates. So thank you for illustrating that in this context.Ethics is the philosophical evaluation of morality.
Morality is the implementation.
And morality should always be re-evaluated by ethics, otherwise morality can take on unexpected exceptions.
As soon as pressure is built up in any way to influence a voluntary decision of another, there can no longer be any question of the person being able to make an unbiased decision. That person is no longer objective.
And Quinn has put Mona under massive pressure, made her downright afraid.
From Quinn's point of view, this is perhaps morally justifiable, and for players who identify more with Quinn, perhaps it is. They might ethically reconsider that given moral stance.
But for the others (I hope it is majority of people) it is morally and ethically not justifiable how Quinn deals with some girls.
Please don't misunderstand me. If a woman chooses prostitution voluntarily (without pressure, blackmail, etc.), that is legitimate for me. If not it is criminal.
Whether the Quinn-pimped-college-prostitution is morally justifiable or not, however, is irrelevant. This issue has a legal side to it. Prostitution in all forms are illegal in almost everywhere in US, save parts of Nevada.
Each individual here can make their own judgement on the morality of Quinn's restaurant, but no one here can and even should dispute it's a problematic issue that will cause almost everyone in that sorority enormous amounts of pain down the road.
Because it is massively illegal.