Anyone who doesn't realize Usui's previous themes of asexuality were deeply connected to internalized lesbophobia... I'm envious that y'all didn't go through it. We lesbians not only grow up isolated, but also alienated. The only type of attraction to women we are taught is men's objectification, so a homosexual woman can go her entire life without realizing about her attraction since we just don't know what it's like to experience, we haven't seen attraction to women without dehumanization. And yes, a whole ton of us do feel disgusted towards our own attraction once we do realize. I myself struggled, still sometimes do, for nearly a decade with this. Before someone else told me I'm a lesbian, I didn't even think it was possible that what I felt for certain girls wasn't just deep affection. So, it is extremely possible we are witnessing in real time a lesbian woman finding herself through her works. I know I can absolutely see my own journey through these pages. Usui is, without a doubt, my favorite mangaka.
Edit: I forgot to mention. For five years, I was only comfortable with saying I was asexual than accepting the fact that I feel attraction exclusively to women, and Crescent Moon and Doughnuts did mirror my own thought process back then.
I don't necessarily think we can/should make any assumptions about Usui Shio's personal life, but you make a good point about her works spanning a wide breadth.
Even before this, every series she's done has approached topics of affection and intimacy from a different perspective and angle. It speaks highly of her skill as an author to tackle different aspects of what attraction, desire, and love actually mean to different people.