I'm going to pull some ideas right out of my behind so feel free to dismantle them.
There is very little brotherhood/kinship between men that allows men to feel sorrow and grief for other men's suffering, and that may be a product of our gynocentric and warlike nature. When "other" men die in wars or conflicts, we say good riddance or fail to spare a passing thought for the men who died, whereas women get a modicum of sentiment and sympathy. Even in such MGTOW places as YouTube, when there is disagreement, some men will jump at the other's neck, so if you expand that to include mainstream gynocentric blue pill men, male suffering isn't important. Who gives a damn if a woman beats a man in public? Certainly not men as they record and laugh. There is a societal expectation for men to deal with personal hardships such as rape, injury, homelessness. There was a post recently on r/MGTOW where a city or something wanted to close down a center/program for trafficked boys (not men). No sympathy or support for these boys, so how can men expect sympathy or support for rape?
In my opinion, men have a comedic/satiric/ironic nature to them that has them make light of certain dark parts of their life and make light of their suffering as coping mechanism. Perhaps other men see that and laugh at it because the guy who got raped himself was joking about it. Men have a sense of humor, where as women don't. Men make light of things, whereas women are so damn serious about everything, buzzkills if you will. Dave Chappele jokes about male rape? We laugh, even though it is a series matter (which women don't sense at all). When male comedians make fun of female rape or make rape jokes that involve women, there is instant outrage, calls for the comedian's head, and calls for change. We see the rise of feminist comedy (which is fucking awful and unfunny). Given the "man up" belief of society, it further covers up male suffering to a point where where we as a society wouldn't know how traumatic male rape really is and instead think it's just a temporary boo boo that will heal easily.
Lastly, this uncaring attitude to male rape victims may stem back hundreds or thousands of years, perhaps ingrained in our very nature. Perhaps the ancient Greeks and Romans practiced homosexuality and male rape and laughed about it. Men are supposed to be masculine and deal with things in a masculine way, whereas women are feminine and are delicate flowers that need coddling and support (man=strong, woman=weak). Nobody likes or can tolerate a wuss, a man that cries, and a man that complains. All male suffering must be met with stoicism. I remember my female relatives would react with sadness when a woman is maimed in a conflict in the Middle East, commenting that maimed men are still men and can still live and make ends meet. Male suffering and psychological devastation is nonexistent to them. He's still expected to contribute somehow. The maimed man is supposed to man up and deal with it, whereas the woman needs all the tears, support, and sympathy she can get to deal with missing arms or legs.
All forms of harm directed at women results in a sea of sympathy and a call to action and rape is just one of these violations that will cause outrage. Even when men die in wars, it's the women who are the true victims. It's the same uncaring attitude we see when men are the majority of workplace deaths. Does society feel bad if men fall off from a building and falls to his death? I think you may find a pattern in the way society and people view male and female suffering. Women are humans and men are human doings.
A woman is maimed or injured? Feel bad.
A man? Man up and deal with it.
A woman loses her job and struggles to make ends meet, perhaps even on the brink of homelessness? Feel bad.
A man? Man up and deal with it.
A woman gets raped? Feel outraged.
A man gets raped by a man? Lol, man up and deal with it. LOOOL.
http://sheddingoftheego.com/2015/05/06/why-feminists-will-never-be-funny/