What he really meant
Purely speculating of course but when I heard the phrase "Legitimate Rape" it seemed to me what he meant was NOT 'forcible rape' the term that's been bandied about and his explanation of what he really intended to say.
I think he, and so many of these men so concerned with controlling women's lives, meant Legitimate as in Honest. Not as in Ron Paul's "Honest Rape", I think he and Ron Paul and the other republican's who've said similar things over the decades mean....
"If we assume the woman is telling the truth."
The default presumption for them is that any woman who claims Rape is lying until proven otherwise.
= new reply since forum marked as read
They really mean "yes"
Or a child who does not know what is going on, or can't say no because the rapist is her father or uncle or brother or baby sitter..
I believe those situations would not be deemed "forcible rape" Therefore, according to the Regressives, not rape at all.
( edited many times because when I am angry, I commit many typos)
"The default presumption for them is that any woman who claims Rape is lying until proven otherwise. "
It is "proven otherwise" if her body "shuts down" so she didn't get pregnant.
If she got pregnant, she wasn't legitimately raped and was lying. She "really wanted it." She "said no, but really meant 
yes." She likes it "rough."