Direct bondi
One of the reasons that Norwegian's opponents in the USA have used is that in their view Irish oversight is weak and that the opportunity for the IAA to inspect Norwegian's operation is limited given that they do not fly to Ireland with EI plate aircraft, not an unreasonable point, SAFA's remit is somewhat different.
I think that with G plates on an UK AOC it would be much more difficult to deny them (Norwegian) open skies rights from the UK and elsewhere in Europe. The UK CAA for all its faults is respected world wide.
In a global economy it is increasingly difficult to define the principal place of business.
So yes i think it would be good to see DY flights with G plates