Tom Spurgeon was informed of this by chair Marc Singer. From the ICAF website (emphasis in the original):
Panel 5: The theory and practice of comics studies
Moderated by Charles Hatfield, ICAF Executive Committee
Ernesto Priego, “The Tell-Tale Smell of Burning Paper: ‘Logic of Form’ and the Origin of Comics”
Benjamin Woo, “An Age-old Problem: Problematics of Comic Book Historiography”
Joseph Witek, “American Comics Criticism and the Problem of Dual Address”
Ernesto Priego is unable to present his paper at ICAF because he has been denied entry into the United States of America. The U.S. government has not renewed his visa, nor have they given him any explanation why he will not be allowed into the country. ICAF protests this refusal of entry, part of a recent and disturbing trend of excluding foreign scholars, as an infringement on academic freedom.
Marc Singer expands on it a little more at his blog.