Selling Dublin in the US?, don't think so way more heavily the West/South West and US airline profiles would suggest T/A out of SNN is important as many fly into one and out of other.
As for APD, you didn't see Dublin crying about zero tax in Belfast at time....why doesn't he write to Ms Foster with similar tone and see how far he gets
It will not result in routes if it goes, just look at ORK/SNN type routes and Ryanair have already said its difficult with DUB close and that will apply to Belfast. Cant see U2 been that impressed with BFS of late so route to cities when yield must be taking a hammering wont happen.
Don't ditch day trippers as they account for massive spend outside Dublin down south as well.
Nobody is forcing NI to pay TI to market it, so get your own politicians to sort out your problems however given the UA mess I wouldn't have faith.