I don't think FKMT was being homophobic I think it's more just endou worrying that GM was going to assault him. In the end nothing bad was said about gay people and more just a joke that endou was thinking way too into this.
This chapter is really funny in an unintentional way. The fish analogy was good, it made sense. But then Kaiji just comes out of fucking nowhere and starts beating the shit out of Kazuya. It happens randomly, I love it.