That's not the message. The message is that how someone is dressed when they are raped doesn't mean they 'deserved it'. Many people at Slut Walk dress in ways that are exposing, but the point of their nudity is to promote the message that "even if I dress like this, you must still receive my consent to have sex with me, and if you don't, it is rape".

They attacked someone not for getting their bits out, but for getting their bits out in a way that was specifically intended to attack and shame the message of Slut Walk. He was not doing this in a sign of deep solidarity and understanding of their message, and it's pretty obvious from his disrespect that he does not actually agree with the message and was very intentionally and maliciously trying to get a rise out of people by exposing them to his nudity in an agressive and taunting manner.

Intent matters, folks. His intent was not kind and he was not just walking around with his junk out minding his own business. They wouldn't have cared if this was a case. He was antagonizing them and trying to tell them, "even in this, your safe space and a place to share your experience with a violent sexual crime, you are not safe from me, and you cannot escape me".

I'm still not condoning the men who hit him (notice that only men actually physically attacked him in the video) but I completely understand their anger.