Joyce was rather catty about Colum elsewhere. In his The Holy Office*, which Ellman describes as a "scabrous broadside", Ellman describes how "With quick thrusts he disposes, more or less thoroughly, of his contemporaries. Yeats has allowed himself to be led by women; Synge writes of drinking but never drinks; Gogarty is a snob, Colum a chameleon, Roberts an idolater of Russell, Starkey a mouse, Russell a mystical ass.
But all these men of whom I speak
Make me the sewer of their clique
That they may dream their dreamy dreams
I carry off their filthy streams
For I can do those things for them
Through which I lost my diadem.

Interesting commentary on the poem here.
* In this poem 'Hazelpatch' should be 'Hazelhatch'