I think I'll just quote the rest of what Connolly says about the matter in chapter 6;
Although he is at pains not to give any credit to Grattan's parliament, presumably because he doesn't wish to align himself with the successors of the Irish parliamentarians of the 18th century, the bourgeois Home Rulers, in the end he concludes;
"That the Act of Union was made possible because Irish manufacture was weak, and, consequently, Ireland had not an energetic capitalist class with sufficient public spirit and influence to prevent the Union."
(Labour in Irish History)
"An Ireland controlled by popular suffrage would undoubtedly have sought to save Irish industry, while it was yet time, by a stringent system of protection which would have imposed upon imported goods a tax heavy enough to neutralise the advantages accruing to the foreigner from his coal supply, and such a system might have averted that decline of Irish industry..."
(Ibid)
So in the end he does admit in a roundabout way that Ireland did not industrialise simply because England would not allow it to, insomuch as Ireland would be her competitor.
Perhaps I'm mistaken in this comrades, but I'm guessing that Connolly's antipathy towards the traditional nationalist view of the Union and it's effect on Irish Industry is because it is, or was, the standard narrative of the bourgeois Home Rule movement, which Connolly was not interested to align himself with. Does anyone have on opinion on this?
"We stand with great emotion before the millions who gave their lives for the world communist movement, the invincible revolutionaries of the heroic proletarian history, before the uprisings of working men and women and poor farmers – the mass creators of history.
Their example vindicates human existence."
- from 'Statement of the Central Committee of the KKE (On the 90th anniversary of the Great October Socialist Revolution in Russia 1917)'