Perhaps the incongruence of the images was somehow planned to interact with Hill's 2004 "Private Passions" BBC broadcast, where music sung at the funeral of Princess Diana in 1997 was immediately followed by "The Star Spangled Banner" as performed by Jimi Hendrix in 1969, during the Vietnam War. Yet, Hill did not mention September 11th in that context, and there is tremendous difference between the events of September 11th and their aftermath.
As an American, it is difficult for me to see images of The Twin Towers used in this way, but maybe that is the point of the poster... Be that as it may, three people are giving papers about Hill's poetry: Carole Birkan-Berz, David Ten Eyck, and Emily Merriman.