Seamus Finucane, who Ms Cahill has accused of being part of an IRA “kangaroo court” which “investigated” her allegation that she was repeatedly raped as a 16-year-old, posted the article by Ruaidri Ua Conchobai on his Facebook page.
The post said the alleged rapist was the type of man “whom many a 16-year-old would likely fancy”.
The post suggested the abuse could be “year-long clandestine sexual relations between these two people ignited by a lawful but ‘a few cans of beer’ induced seduction by a silver-tongued, musically talented, IRA-powerful type of charmer whom many a 16-year-old would likely fancy... It’s possible but I don’t know, do you?”
Ms Cahill reacted angrily to the move, and demanded Sinn Féin condemn the sharing of the blog and offer an apology.
Ms Cahill confronted Sinn Féin deputy leader Mary Lou McDonald over the post on Twitter and asked her to condemn it.
Ms McDonald replied: “The assertion in that blog is shameful and cruel and should not be posted anywhere by anyone.”
Fianna Fáil justice spokesman Niall Collins said it was deliberate intimidation intended to stop others coming forward.
“This is clearly part of an orchestrated campaign to undermine Maíria’s credibility, but this takes things to a new low,” said Mr Collins.
“It is disgusting and it is also a clear attempt to intimidate other victims who may be considering coming forward. When I read it I was speechless.”
Labour’s Joanna Tuffy told Sinn Féin to “stand down their key board warriors” and stop harassing Ms Cahill.
“The online smear campaign being undertaken by sources associated with Sinn Féin, suggesting that Ms Cahill was in some kind of consensual, lawful relationship with the man who raped her, marks a new low in this sorry debacle,” said Ms Tuffy.
The row erupted as Sinn Féin’s deputy first minister in the North, Martin McGuinness, said that he believed Ms Cahill had been raped.
However, Sinn Féin MLA and Stormont junior minister Jennifer McCann said that, when she met Ms Cahill in 2005, she did not mention the kangaroo court allegations to her.