I'd put money on Breathnach over Coin and Egan, for sure. Where is their specific evidence? There is so much unsubstantiated mythology concerning the pipes in both Scotland and Ireland that it's hardly surprising that otherwise decent authorities sometimes just repeat old wives' tales (or in this case, old Grattan Flood tales), even when they really should know better. Repeat something often enough, though, and all sorts of people will start to believe it just because it is said so often. That really does seem to be the case here, unless new evidence has emerged very recently.