Certain sexual expressions (probably better worded as gender expressions) would be say, wearing overtly male clothing in the home.Evidently, their only request was that their child not be themselves in their own home.
I can't speak to "certain sexual expressions" because I'm not familiar with those.
The parents tolerated her continued residence in the home despite being 28 years old and spending money on a kewl car instead of say, a rent down payment. They might have been aware that not all her "art work" was exactly affirming conservative Christian ideals.
I suspect that the parents were not insisting on "Little House on the Prairie" style feminine clothing in their home. Rather, gender blurry clothing could well have been acceptable- though probably not preferred.
In short, the parents were apparently willing to let AD "be herself" to a large degree while in their home (not Ad's home). But, that willingness had limits. It was not a blank check.