The issue here isn't about sex at all or sexualization. Sexualization is given as the reason because that's all men can see breasts as. If you look at it from a dog's point of view, or a baby's point of view, it's a source of food or just another thing and you may start to wonder what the big deal is with making breasts bigger or even showing them.

The issue of contention here is that women have to adjust their behavior/physical appearance over some non genitalia body parts because it happens to induce sexualization in some men, and men don't have to cover that same body part.

What if the majority of people were sapio-sexuals instead of breast-sexuals? Do I need to start dumbing down my HN posts so that I don't be perceived as immodest? Given the diversity of sexual preferences where do I draw the line of accommodating others' sexualization boundaries?

For the record I agree with you on genitalia, because at least both men and women are not allowed to show them. But breasts? It is not genitalia—it is not even used in the act of sex (normally)!