It's a key part of the MRA agenda. Some MRA even say that men are as often victims of rape by women as women are of rape by men.
I absolutely agree that sex should always be consensual,and if a man has been forced, by either physical or psychological means into sex, then he has been raped and deserved of course to be taken seriously, and for the perpetrator to be charged and ,nif found guilty, convicted. And I know that an erection is a physiological response, and does not necessarily mean that a man actually wants to have sex.
But the MRA are full of stories of men waking up after falling asleep drunk at parties to find women on top of them. And vqriations on th them of being forced to penetrate against their will. And, it might just be my misandry showing, but really? Does this happen a lot? Is it a really serious problem that needs to be addressed, and have equivilant resources given to it?