That Irish government spokesperson would have been talking in favour of the treaty, so I'd take that with a pinch of salt.

My understanding is that enlargement can go ahead without theat treaty, and that most opponents of the treaty are in fact in favour of enlargement to admit Easstern European countries. Opposition to it seems to have centred on the suspicion that a lot of other stuff had been sneaked into it which threatened things that are valued in Ireland, such as an ability to keep out of foreign wars.