If your child went to TCD as a post graduate student and got a PhD they would get it from the University of Dublin, not from Trinity College Dublin, because the University, not its sole college, is the conferring authority.
And if they wanted to sign a petition and add their degree on, even though their current job was not in a University, their Degree would have to be listed as 'PhD University of Dublin.
Which is how everyone styles it.
I doubt the person conferring the list had anything to do with it. The artists used the correct wording. Making himself seem a bit presumptuous imo, unless something in a degree he took at some time in the past is relevant to the treatment of modern teenagers.