Not solely culpable, but everyone is responsible to a considerable extent for how they present themselves, and if one speaks on behalf of a group, yes, their actions will to some extent reflect on the group.

I mean when Michael Knowles says something hateful and ignorant, do you think, "Oh wow, I can't believe Mike is saying that garbage" only? Or does his antagonism reflect badly on the entire right wing perspective on trans people?

I'm not "dictating" to you, just reminding you how societies work. If you are abrasive and uncharitable, that will reflect badly on you. If you are understanding and welcoming, that will reflect better on you. If you are abrasive and uncharitable while saying you're part of some community, it will reflect badly (very slightly, unless you're very prominent) on the community, too. If you are understanding and welcoming while saying you're representing some community, it will reflect well (very slightly, unless you're very prominent) on the community, too.

Do you honestly think that it doesn't work this way?