God I hate the lack of multiquote.
One person is born into a world in which the lifelong message is that they're second class. They're told not to take math because they won't need it to become a baby-making machine, or maybe that they'll just end up in jail anyway because that's the way the system is. Hard work doesn't matter because you're not the right type of people.
I want to isolate this because this is a pretty good distillation of the actual problem. The solution here is to teach girls to take math, it's to teach girls not to be scared of math, and it's to teach them that before they're old enough to drop out of school. It's vanishingly unlikely that an eighteen-year-old that's lived her entire life hating math is going to find out she suddenly loves calculus (theoretical math being entirely different notwithstanding). Yes, it can happen, but it would be disingenuous of us to believe it's all that common.
Cultural cherry-picking is "the ends justify the means" discrimination, but it's still discrimination. It doesn't send the right message when there's a woman on the panel because "they needed a female". Panels should always be unbiased samples. It's the population that needs to be changed, not the sample.
USCs state of affairs is made worse because by canceling the event, they've all-but-disclosed to the world at large that they did, in fact, need a token female.
Well you're making the assumption from the start that people with no interest are going to be pushed into a field...
Most people would instead see it as not pushing people with an interest out of the field.
If we stop pushing interested people away, then the number of people who hate the field and are just in it for the money will obviously decrease... which is the opposite of what you fear.
They're not mutually exclusive. I'd say they're doing both, and the two don't cancel each other out at all.