To deny that sexual assault happens against men is to live half-blind. Sexual assault in all cases is about power and gratification by abusive individuals (spread equally among both sexes) against the vulnerable of either sex (and the gender matters little to them).
Edit: corrected the figures.
That stat's not in that article.
https://en.wikipedia.org/wiki/Rape_by_gender#Rape_of_females
"In a 2000 research article from the Home Office, in England and Wales, around 1 in 20 women (5%) said that they had been raped at some point in their life from the age of 16 beyond.[6]"
https://en.wikipedia.org/wiki/Rape_by_gender#Rape_of_males
"The same study found that approximately 1 in 21 men had been made to penetrate someone else, usually an intimate partner or acquaintance."
This is completely in line with original claim, "have been forced into sexual intercourse against their will". Wiki page does call this rape when it comes to women, but not when it comes to men.
Source: http://www.cdc.gov/violenceprevention/pdf/nisvs_report2010-a...