What I kind...a little telling about the LW's approach is that they did not attempt to figure out either modern Irish culture, or the Irish culture of their ancestors -- they attempted to figure out modern Irish-American culture. That culture is as assimilated as fuck to whiteness.

Excuse the fuck out of me? What does "assimilated as fuck to whiteness" mean? There IS, in fact, a modern Irish American culture. As it happens, most modern Irish Americans are white, as well. So were the Irish historically. I think you're trying to conflate two different ideas of what "culture" is here. Have contemporary Irish Americans assimilated into US "white" culture? Yes. Does that mean they don't also have a culture of their own? No.