I don't think that's it, it's just Shikkari's kind of wired to find the masculine look more attractive due to her years and years of being a yaoi/boy love fan, especially since Futantei resembles one of her previous oshis. She knew Futantei was a girl when she offered to live with her and has shown affection towards her in the previous chapters, despite that. Plus she said she wanted to see Futantei in a skirt this chapter.
Yep, lesbian couples consisting of one butch woman and one femme one happened/happens often enough that it became a stereotype here in our real world even.
Funatei just casually lifting up Shikkari's skirt was pretty funny, especially since she seems to be taking a serious look at Shikkari's panties in the process.