He didn’t say “must have” on the previous page, he said “more likely to have”. There’s a difference!
It wouldn’t prove anything conclusively, but that fact that it’s not considered at all is troubling – especially since I strongly suspect the argument “I haven’t had a one-night-stand before, that proves I’m not that kind of girl!” would be accepted.
The Rape Shield as described verifies this. Someone who is sexually promiscuous can’t have that used as a way for someone to commit rape and it be unprosecutable. That would be a seriously dangerous precedent for obvious reason. But lack of any such history is reasonable cause to doubt that consent was given, and there’s no similar danger in that defense.
Presumably, if lack of any such history is claimed, the Rape Shield would have to be weakened enough for the counter argument to be presented… ie, “I don’t mean to be indelicate, your honor, but the prosecutor’s client does have quite the reputation.”
After all, the danger that an innocent man might go to jail and the danger that a guilty man might not are pretty similar to each other.
I seem to recall hearing that there’s a rule allowing you to bring in evidence that would normally be excluded if you’re using it to disprove a witness’ testimony. (“Impeachment evidence”)