My mom let me see this ballet when I was nine. I didn't feel like I was being scandalized ...
So, this is why women cannot be theologians, much less moral theologians. Theology works on principles, not on whether you FEEL like you were being scandalized, and not wanting to admit that your "mom" might have done something immoral -- a bunch of emotional reasons bundled together.
We on the other hand simply read the directives issued by that congregation under Pope Pius XI (the last Catholic guidance I'm aware of) ... and apply the principles. It's not about FEELINGs.
Now, with that said, there is one aspect of moral theology that is somewhat subjective, where something could be a near occasion of sin to one person that is not to another. But that's not relevant to the principles, but merely specific applications of principle.
This does not mean that you can go to watch strippers simply because that does not constitute an occasional of sin for you ... since there are other aspects of moral theology, including scandal, and simply the harm one does to his own sensibilities regarding right and wrong, and just being IN an environment with grave sin being inherent in it, that's sinfully inappropriate for a Catholic regardless of whether or not it constitutes a grave occasion of sin. Yes, most of us likely COULD go to a ballet and not have it constitute a grave occasion of sin, especially since, depending on your seats, one might have a different perspective on it. But simply attending such things suggests that we approve of them or consider them to be acceptable and licit, which along suffices for forbidding Catholics from attending.