There may be a little more to it than that - maybe some payback is involved.
"A damaging rift appeared in Ireland’s Catholic hierarchy as Archbishop Martin – who had opened secret church files to investigators – publicly called on clergy implicated in the state inquiry to step down."
(Irish Echo)
"Multiple speculations on the significance of the rejections have circulated in the news, with one Irish editor commenting that the Vatican was not pleased with Archbishop Martin's public clash with predecessors and other Church authorities. The archbishop, who was appointed in 2004 amid Ireland's child abuse scandals, has been outspoken against implicated Church officials who suppressed reports of abuse and transferred abusive priests to other parishes in the U.K. and the U.S.
Gary O'Sullivan, editor of the weekly Irish Catholic newspaper in Dublin told the AP that the “Vatican were not impressed with the way Diarmuid Martin went on PrimeTime (an Irish television news program) and called on other bishops to be accountable.”
"It's not the way business is done in Rome.”
(CNA)
It seems that the Vatican is not pleased with Archbishop Martin and this is a way of showing its displeasure.
Diarmuid Martin spent much of his career floating around the UN, the World Council of Churches and the IMF (yes, that’s right). He was a Vatican diplomat until 2003, when he was assigned coadjutor to the retiring Archbishop of Dublin.
He got to be Archbishop because he was the coadjutor and automatically succeeded when his predecessor resigned. He was formally appointed by JPII the year before the death of the latter, when JPII was already very sick. Since then, Benedict XVI has consistently refused to make him a cardinal.
He is only dubiously loyal to the Church’s teachings in a lot of areas but he usually manages to say it carefully and ambiguously enough so that he won’t be slapped down immediately.
He’s basically going on a finger-pointing campaign. He’s trying to do what Rembert Weakland did - shift the blame for everything to others. He has a grudge against BXVI for not naming him a Cardinal and has been consistently hostile to the Pope, who attempted to address the matter as a problem with the entire Irish system of Church governance instead of seeking out a couple of individuals to throw to the media.