QC

"What other people do in the privacy of their own bedrooms is their own business" is a bad argument for sexual tolerance, because it's not true and has never been true. We obviously care a shit-ton about other people's sex lives and always have.

(CW frank discussion of sex and nonconsent)

People care about whether other people are engaging in unethical behavior, for lots of reasons, but one is because we care about each other. The important caveat "...as long as it's between consenting adults" points clearly to this.

If you think a certain sexual behavior is unethical / hurtful, it's normal for you to care whether other people engage in it, whether that behavior is homosexuality, kink, rape, pedophilia, whatever. Sex has always been a key ethical concern.

That is: if you think it's your business whether other people engage in rape or pedophilia, then you've already conceded that in general you think it's your business what other people do in the privacy of their own bedrooms.

The privacy argument deflects from the uncomfortable heart of the matter, which is: we don't agree about ethics (in this case sexual ethics), and moreover we don't have a shared cultural mechanism for coming to agreement about ethics.

Some people implicitly seem to want consent to be a foundation for ethics. This is pointing in a good direction, but consent as it stands today cannot bear this weight. There is so much murky territory waiting in the question of what it means to "really consent" to things.