According to this wikipedia page(Adirondack Mountains - Wikipedia), they aren't... That's where I got my info. Although, wikipedia has been wrong before.
Until you said "many, even locals, think the mountains in question are indeed Appalachian." I, too, believed that the Poconos, Catskills, and Adirondacks were all part of the Appalachians.
I have some of the McLaughlin from that link and I cannot, for the life of me figure out how to clean it off anything. I put some on my keg lid and now that o-ring is trash unless I can figure out how to get rid of it.