I’m sorry, but even if post-canon Mike were secretly queer, the argument that “If Will is allowed to explore his sexuality outside of Mike, then Mike should be free to have crushes on other boys too” is kind of ridiculous.
While this may seem fair on the surface, some people, in their tunnel vision regarding what they perceive as unfair treatment of Mike by 20 willstans, seem to overlook that it’s Will who is a visibly queer teen living in a world that does not accept him. In contrast, most of Mike’s struggles in the story revolve around his feelings of inadequacy and insecurity in his relationship with Jane/El. Unlike Will, Mike does not question his identity; he is not forced to confront any internal contradictions or engage in any self-reflection. After two seasons of struggling, he conveniently gains confidence from Will’s painting, but the writers never address this development again.
Will has endured years of heartbreak and rejection. Moving on is crucial for his self-preservation and growth, as it aligns with his journey of self-acceptance. In Seasons 3 to 5, he clings to the idea of the Mike from earlier seasons and the childhood intimacy they once shared, even though Mike prioritizes Jane/El over him. Will experiences profound pain related to his identity--internalized shame, forbidden love, and the feeling of being a mistake for being different--while Mike primarily struggles with typical teenage insecurities.
You have a canon queer character who has been treated poorly, but your focus is still on Mike, who has never confronted how he has hurt Will, both intentionally and unintentionally. Everyone should rewatch the rain fight in Season 3 without concentrating on Mike’s imagined struggles. Will has carried shame and fear since childhood. In the first episode of Season 3, he expresses that he is not going to fall in love because he already feels different and “not normal.” He experiences isolation while his friends enjoy their first heterosexual milestones, such as having girlfriends and kissing. When Will tries to stand up for himself and calls out Mike’s bullshit behavior, it backfires. Mike responds with the same derogatory language that bullies have used against Will. Instead of admitting that he hasn’t been himself, Mike shifts the focus to Will’s “difference,” leading to a soul-crashing breakdown for Will in what was once his childhood safe space. He realizes that nothing can ever be the same; he does not like girls, and he is in love with a boy who cannot reciprocate and is actively leaving him behind. In Season 4, Will’s crisis continues while Mike, self-absorbed, fails to notice the signs.
Fantasizing about Mike’s crushes on other guys comes from a desire to portray fanon Mike as a more complex and interesting character than he is in canon. However, their dynamic is already imbalanced, and instead of creating unnecessary drama, it would be more productive to envision Mike actively working towards a healthy relationship with Will rather than calling out the “unfair treatment of a deeply repressed babygirl Mike” by these horrible willstans.