I think the yearbook thing wasn’t connected to the original (paid for IMO) accusations. I think the woman just saw opportunity and took it.
She was actually a gift to Moore because her “proof” is so shoddy. The others would have been harder to refute because it was “he said, she said,”.
Frankly, the signature in the yearbook* is not proof of sexual abuse. But the photo of Franken is.
*though if forged it is proof of Slander