For instance, staying with the bisexual theme, let's say the point is to get full recognition from medical providers that bisexual men are at higher risks for some medical problem. Let's assume that gay men aren't supportive of this for whatever reason. So, the movement has two distinct targets, medical providers and gay men.
If the idea is to get them to change their perspectives and you only have bisexual men in your network, how then can you understand the mindsets of the opposition? Assumptions will not go over well and will not be effective for the outcome. So you must not only listen to them, but you must include them.
Whatever the movement is, inclusion of diverse people is necessary to win the support of neutral constituents and understand the mentality of the opposition. When you fully understand the reasoning behind their actions of thoughts, then your diverse constituency base will be most useful in strategy development.
I'm not saying that if your a person of color equality activist to go to a white nationalist and include them on your board of directors. What I mean is, if your a black activist seeking equality, you cannot rule out the inclusion of white people. This stands for any cause, feminist, LGBT, Natives, immigration reform etc.
Factor in ways for supporters to help. Some folks want to be apart of your cause because they believe in it. But they don't have to be you.