The problem with this is you continue to assume that the woman is dressing sexy for someone else, rather than for herself -you are actually the one objectifying her. You are correct that there are many instances that are not truly empowering, but those aren't the only reasons that women post half naked pictures or wear sexy clothing.
I used to go to a private club where it was common for women to wear not much at all, and it was incredibly empowering. It gave me back my sense of my own body as belonging to me, and reclaimed my sexual self from a world that had always told me that was for the benefit of someone else.
"She is free to be as sexually forward or expressed as she wants with no slut-shaming or entitlement. What she has on isn’t seen as an invitation. There’s no assumption that she is dressing to get male attention. Women dress sexy to have the enjoyment of owning their sexuality in a semi-public venue and she may or may not share that sexuality with anyone else present and that is considered completely acceptable."
As E. L. Byrne said in her marvelous story, My Sexual Liberation Doesn’t Belong To You, “Once I accepted who I am and how I want to express myself sexually, I could show myself to other people and be truly seen for the first time.” I have some friends, strong, feminist women, who enjoy posting pictures of their body in various states of undress on the internet. That’s not the way that I express and claim my sexual self in the world, but I totally respect and honor that it is theirs.
There can be no equality without freedom — and the freedom to inhabit and share this very fundamental aspect of humanness in the way that any woman wishes to without censure and without entitlement is a cornerstone of that.
You don't get to determine what is empowering for someone else, and your thesis is essentially reinforcing the right of the male gaze to be the only one that counts. It's taking power and agency away from women. It's reinforcing that women only exist for the approval and enjoyment of men. The way to change that element in our society is not by telling women to further curtail their sexuality; it's by helping them find ways to express it how they want to for themselves.