Well, it's probably a step backwards in transparency, but given the tone of the article, it probably means that Bank of Ireland are thinking of bumping up their ECB tracker rates soon. I'd be doubtful if AIB would be the "senior" source of this article.
An interesting alternative that retail banks could consider is offering mortgages tied to one month Euribor. Most customers make repayments monthly so this should not create a major issue for customers, while it takes out the basis risk that Banks have in that they cannot fully hedge the difference between ECB and Euribor, the latter being what Banks effectively lend each other money at. The Euribor fixing is calculated daily and is a published rate in the way that ECB repo rate (4%) is. So there remains full transparency.