You can't argue rationally with emotion or narcissism. The vast majority of the population has zero interest in trans people and they can't stand that, and bisexuals who do aren't validating enough because they're attracted to both sexes. They need a lesbian because lesbians can only be attracted to females, so this validates their autogynephilic fantasies to the max. All these arguments were made secondary to them having uncontrollable boners for the idea of a lesbian fucking them.