I wouldn't say that the roommate necessarily identifies as male. They say "you don't really need to be a male" when talking about their male marked ID. They purposefully leave the situation ambiguous, likely to minimize the friction of needing to stay in the "male" dorm. They needed to dorm somewhere, and likely couldn't stay in the female dorm as someone who was AMAB, so they chose to room with a childhood friend and act coy when pressed about their gender.
There's also the fact that the author is almost certainly trans herself. She doesn't advertise her gender on most socials, only having it listed on Pixiv, but a brief look at the past profile pics for her Facebook group paints a timeline. She's posted a number of gender related comics, including a very dark one about Onimai that I don't have on my phone right now.
My suspicion is that this comic reflects the cultural context that she currently exists in. Keeping her identity on the downlow allows her femcel shitpost comics like Brainrot GF to reach a wider audience, many of whom still refer to queer characters with slurs. Senukin needs the money and doesn't need the controversy, so she does exactly what this character does.
It's ok, I've been there too. I used to wish I was trans, but I was scared that I was just looking for an easy solution to my problems. It wasn't an easy solution, not because it isn't everything I was hoping for, but because it is not easy being trans. Even though I was convinced I wanted HRT from the day I came out, I let myself get fucked around by American health insurance for over a year when I could've literally paid a few hundred dollars to get it far quicker. There is a damn good reason that I celebrate the CEO assassination.
Since I came out, I've actually looked into the science as best I could. I've realized that the entire system is fundamentally limited, from the way we classify disorders, to the way we even understand evolutionary classifications. It's all made up, because at the end of the day, they're just tools we created.
Our entire understanding of everything from identity to particle physics is constructed to serve. At a neurological level, we build a simulation of reality to better survive in it. The spoon only exists in our mind; the form isn't real.
We cannot choose how we feel about our gender; no free will there. Your doubts and misgivings about anything have the ability to protect, but they can also harm. Consider how these doubts about your identity are working out as tools to benefit you: Are you better off because of them, or are they chains tied to a sinking rock?