They need to be included because they are not heteromantic heterosexuals… that’s pretty much the bottom line tbh. No matter what their romantic orientation is bisexuals are going to recieve marginalisation and society will make them feel broken for not being hetero in every respect of their lives. All excluding them does is deny them resources and visibility that they never get from the vast majority of society and policing more people out of a community that would benefit from more people being members of it.
The B in LGBT stands for all bi people, whether biromantic or bisexual, if you leave any of them behind because they don’t fit this bullshit standard of “bi enough” you’re not doing your job. No bi left behind!