I'm interested that this warrants a return. Unless of course there was a fluid loss or it impacts continuing operation, why not carry on to destination? You've got to land with the problem so why not plan/discuss for 5 hours and do it where your pax want to be? I EMPHASISE only if there was no immediate opertional impact (ETOPS requirements....?)
As one of the commenters on the newspaper article said, is the cost of all the diverts and DUB closure going to be passed onto the (bankrupt) airline? If it was "urgent" (hence return) why DUB and not SNN?
Before anyone jumps on me, I know I wasn't there, I don't have all the facts - I'm just asking for opinion. But well done to the crew for getting safely back on Terra Firma