Can the Oireachtas 'prohibit' an EU Regulation?

I'm trying to make sense of the Minister for Children's statement

https://www.gov.ie/en/press-release/c5585-statement-regarding-commission-of-investigation-mother-and-baby-homes-and-certain-related-matters-records-and-another-matter-bill/

The legal advice received by the Department is that the GDPR right to access personal data (Article 15) is expressly prohibited by section 39 of the Commissions of Investigations Act 2004.

While stated as a prohibited by the 2004 Act, this seems to mean the Act as amended by an Act in 2018, which inserts the following wording into that Act

http://www.irishstatutebook.ie/eli/2018/act/7/section/198/enacted/en/html#sec198

"Article 15 (Right of access) of the Data Protection Regulation is restricted, to the extent necessary and proportionate to safeguard the effective operation of commissions and the future cooperation of witnesses, in so far as it relates to personal data (within the meaning of that Regulation) provided to a commission"

Article 15 is here

I didn't think that the scope of EU legislation could be limited by a national parliament. Otherwise, the EU could hardly function. Our own Constitution is pretty clear on this

http://www.irishstatutebook.ie/eli/cons/en#article29_4_6

No provision of this Constitution invalidates laws enacted, acts done or measures adopted by the State <...> that are necessitated by the obligations of membership of the European Union

If our Constitution is explicitly subservient to the obligations of EU membership, it surely follows that any Act of the Oireachtas (that draws its authority from the Constitution) are similarly subservient.

In particular, EU Regulations have direct effect in Member State laws - unlike Directives, they don't need to be transposed by Member States.

https://ec.europa.eu/info/law/law-making-process/types-eu-law_en

Regulations are legal acts that apply automatically and uniformly to all EU countries as soon as they enter into force, without needing to be transposed into national law. They are binding in their entirety on all EU countries.

That seems to flatly contradict the idea that the Oireachtas could "prohibit" GDPR.

Our own DPC seem to be saying something like this

https://www.irishexaminer.com/news/arid-40070054.html

“The Minister admits that he went back and forth with the Attorney General and that the 2004 Commissions act requires that the records be sealed,” a source with knowledge of the matter said. “But that act came in 2004 - it predates the EU’s charter on fundamental rights and GDPR and the 2018 data protection act, and where there’s conflict between national and EU legislation, the EU takes primacy,” they said.

So it just seems plain wrong, maybe even nonsense, to be talking of an EU Regulation being "expressly prohibited" by an Act of the Oireachtas.

So I suppose my question is - is there any possible explanation for this seemingly nonsensical legal advice?