This is a very popular form of biphobic rhetoric. Having encountered it in several places during the past week, I figured that formulating it here might be helpful for people.
The bisexuality=oppressiveness equation refers to any argument relying on the presumption that bisexuality is an oppressive identity, or that bi people as a group, occupy oppressor status in relation to nearly every other group.
For example, the “bi is binary" argument relies on this presumption, because it presents bisexuality as an identity that inherently oppresses trans*/nonbinary people, and insinuates that all bi people, as a coherent group, oppress trans*/nonbinary people.
Another such argument is that bi people are privileged over gay and lesbian people, that bi people benefit from heterosexism and patriarchy, and therefore have oppressor status over gays and lesbians.
Another such argument, which has been receiving certain currency in some Israeli communities lately, is that bisexuality - as a term, as an identity, and as a coherent group - is oppressive towards ace people (because it contains the word “sexual”).
The most sophisticated thing about these arguments is that they rely on intersectional political language - that is, they use the “right” terms and the “right” kind of language. Many times that makes it harder to expose - simply because it comes in the form of “calling out” of privilege rather than any the “classical” forms of biphobia that we’re used to encounter. And as intersectional politics instructs: when we’re being called out, we tend to listen.
In light of this, here are a few things that help me pay attention when this is what’s going on:
If I notice that bisexuality is mentioned only in a negative context - for example, in my book, I mention several trans* books that only mention bisexuality once in the entire volume - in the context of criticism of “gender essentialist” (or otherwise problematic) identities.
If I notice that only bisexuality is criticized about something that many more identities/groups share - for example, as in the broad discourse of “bi is binary”, when binary identities such as straight/gay or even man/woman don’t get even a fraction of the bullshit that bi people get. For example, in my life - the “bi is binary” argument has come up every single time I have spoken to gay/lesbian/queer audiences about bisexuality. In contrast, I have never seen this brought up when gay, lesbian or even cishet people (!) speak to similar audiences.
Another good clue is if the person or text in question also echoes other biphobic perceptions, for example that “everyone is bisexual, really”, that “no one is bisexual actually”, that bisexuality is dissmissible/unnecessary as identity, or other attempts to disseminate bisexuality as an identity/group. (This group of arguments often particularly go along with this equation).
Another point worth mentioning is the ease in which these arguments are received. Once someone makes the bisexuality=oppressiveness argument, their argument is immediately well received and accepted, whereas the contrasting argument, bisexuality≠oppressiveness, is always encountered with much resistance and negation.