The Kid is telling us that the reason rape convictions are falling is because defence counsel can't bring in evidence of the alleged victim's previous sexual history, so juries are letting rapists off because they can't tell their whores from their virgins, and of course everybody knows only the chaste get raped, everyone else is Just Asking For It. (Sorry if that sentence is a bit yeah but no but.)
The source is this story and if the Kid had bothered to read it before going off on his usual sixteen going on sixty rant, he would have learned that it is "over-estimation of the scale of false allegations by both police officers and prosecutors which feeds into a culture of scepticism". Only 14% of reported cases actually get to court, so juries rarely get the chance to decide.
The Kid concludes:
Unfortunately, the politically correctness that dares not admit that a woman who has half a dozen sexual partners a month is more likely to have consented is now taking precendence over this fact in the minds of our legislators. The effect of this trend is not, and will not be, more guilty rapists convicted, but more guilty rapists walking free, because the credibility of their accusers could no longer be established.
The point is though, that the discredibility of the accuser is the main focus of the police and the prosecutors, to the detriment of evidence gathering and case building.
A rather less excitable conclusion than the Kid's, of course, who, bless him, never allows the facts to get in the way of a good rant.