dude, i have no idea what or where you're talking about.
a) sexual assault is treated pretty much the same in various spaces that i've been in: it's both valorized as something that is horrible, and not addressed because it's complicated and difficult and people would rather not deal.
b) to the extent that it is maybe different for anarchists than from strictly straight society (wetf that means), the accusation of it is used as a bludgeon (aka some events that happened in ny, at least as far as i can tell given that i'm not in ny and am only hearing about it third and fourth hand where someone who was actually agreeing that there was a problem was beat with a baseball bat by a group). obviously that is not common, but the reasoning behind it is, i think, pretty common. which is that men are guilty, women are innocent, and anything goes in defense of innocence.
where on earth do you get the idea that people are silenced in anarchist groups (or at least any more or differently from other groups/scenes)? home of the accountability process, etc...
as to how to change silencing in whatever scene, who knows. fight patriarchy and shit. one of the things that i want to see happening, around lots of complicated conflicts, is people talking about the issue before it becomes a crisis, and discussing (for example) what they would do if abuse and/or the accusation of abuse happened. small groups of friends, not big groups of strangers, so that the conversations are more nuanced and culture specific. one of the goals being to avoid having to call the cops, who of course, generally make things worse.
anyway, this is a huge topic. pamphlets have been written.