I'm be honest this isn't really that much of a departure from the actual thrust of the book. Straight guys hiding from their alienation and retreating in to hypermasculine nihilistic violence because of the emptiness of their lives, and how that is ultimately unsatisfying and self destructive, is the core thing being examined in the book. They've even got Bob who takes up brutal fighting and ultimately dies, gunned down because he was doing stupid shit to prove his masculinity, all because a medical treatment caused him to grow breasts. The whole book is dripping with the putrified gender of late 90s masculinity. It's not a trans narrative, but the same events could be interwoven in to a trans narrative very well. I guess you could maybe even phrase it as an evil mirror to trans liberation and gender liberation; cis men so alienated by the failed promises of man-ness that they create a new self-annihilating hyper-male gender that they think will reflect their authentic selves. But because it's based on reactionary thinking and an unexamined embrace of inherently self-annihilating aspects of late 20th century masculinity, instead of liberating themselves they make something worse and destroy themselves and everyone around them. Like Tyler is the masculine identity Jack/the Narrator thinks he wants, but by the time he realizes how horrible it is he's already destroyed his life and the people around him and unleashed a societal force of destruction he does not control and that exists beyond him.