I’ve been getting this question a lot, and to be honest I would rather leave that totally open to your own interpretation? Fightclub AU Rick is trans if you want him to be trans.
Personally, I love trans Rick headcanons (and trans Stan too) and I am open to any of my AUs and headcanons being interpreted as trans Stanchez. I generally prefer to leave that up to the viewer to decide. As far as I’m concerned, whether one or both of them are trans or cis, it’s still a love story between the same two men.
(Side note: The bandages are mentioned plot wise in the ficlet to be there because he was shot sometime between parts two and three of the story, but he may also be binding with them or have mastectomy scars underneath. Feel free to interpret it however you want.)