So what? I've signed up for free Amazon Prime just to get something delivered faster, despite having no intention of continuing after the trial ended. Amazon (presumably) knew that was a possibility when they made the offer, just as Quinn knew Maya wasn't interested in sorority hijinks when she asked if Maya was interested in free tuition.
It's relevant because the list was the condition for free tuition.
When the sorority offers free tuition (even if it is part of a scam), then yeah. Quinn never said Maya would be literally whoring herself out, when Maya asked for details Quinn dropped the subject. Thus as far as Maya was aware, the only requirement was that she had to become a HOT.
Maya didn't trick Quinn into revealing the free tuition and then force her to extend an offer. Maya heard rumors and asked, then agreed to the deal that was presented to her. That just isn't manipulation, no matter how much you hate Maya's reasons for doing so.
Also, I think it's extremely likely that Quinn did indeed spread those rumors. She had an obvious (if stupid) motive to do so and never does anything to quash them. Also, unlike Maya, Quinn has a documented history of manipulating people through deceit.