Why wouldn't they, lets say 2-3 years pass and EI say yes this is working and they also need pilots back in Ireland. They would hire UK pilots because some pilots for this operation might not want to fly the services but given the sector issues have decided to do it.
If there is 2 aircraft year round at MAN they would have no issues hiring locally and then prehaps have Irish pilots crew for seasonal based units.
I think if MAN works out but became a highly seasonal operation like Shannon then questions about hiring UK pilots verses more Irish might tip the balance towards crewing by Irish based and maximize flexibility.