Reducing the issue down to a penis is pure sexism.
Men are human, not walking talking penises. Men a good, normal, and healthy minded. Rapists are crazed psychotic criminals, they are not normal men, not normal humans, they are (I expect, and have certainly never met one who I was aware of) plotting psychotics.
Rape is a violent, and horrible crime, and an assault, and a war crime. But as assaults go, how much damage can an erection do? If there is a beating then the beating does the majority of the damage, if there is a disease passed then the disease is a living creature and has some responsibility for an infection but the rapist has more, if there is a gun shot or stab wound then those weapons caused the physical damage. The psychological trauma from a rape is the main damage that I’ve seen in a rape victim, and that psychological trauma can happen to any victim of an assault, rape isn’t distinct in that way.
Recovery from the psychological trauma is difficult, but it is possible, take the reporter Lara Logan as a famous example. I sympathize with all victims of assault equally without prejudice against any men suffering from psychological trauma, nor against any non-rape victims, nor against any rape victims. 
But reducing men, or criminals, down to a penis is purely sexist! Please people don’t buy into that dirty tactic.