Retiring President Biden hit the shops on Black Friday and surprised onlookers by picking up a copy of a book describing the establishment of Israel as “colonialism” that’s been met with Palestinian “resistance” — an acquisition its author bemoaned was “4 years too late.”Biden, 82, left Nantucket Bookworks holding in full view of the press a copy of “The Hundred Years’ War on Palestine: A History of Settler Colonial Conquest and Resistance, 1917-2017” by Columbia University professor emeritus Rashid Khalidi.The book argues that “the modern history of Palestine can best be understood in these terms: as a colonial war waged against the indigenous population, by a variety of parties, to force them to relinquish their homeland to another people against their will.”Khalidi, who is of Palestinian and Lebanese descent, refers to President-elect Donald Trump’s first administration as a “mouthpiece” for Israel and accuses Israeli Prime Minister Benjamin Netanyahu of leading “the most extreme government” in his country’s history.The Arab Studies academic slams what he describes as slanted press coverage in favor of Israel.“I do not speak to the Post (or the Times for that matter), so this is not for publication, but my reaction is that this is 4 years too late,” Khalidi told The Post, which did not offer or agree to any terms conditioning that response as off the record or on background.It was not immediately clear if Biden purchased the book or if it was given to him while in the shop — after he and first son Hunter Biden, 54, dined with first daughter Ashley Biden and other family members at the nearby Brotherhood of Thieves restaurant ahead of the island’s annual Christmas tree-lighting ceremony.Biden has repeatedly referred to himself as a Zionist, meaning a supporter of the Jewish movement that spurred immigration to the Holy Land, leading to the establishment of the state of Israel in 1948.“You don’t have to be a Jew to...