COLUMBIA, Mo. (AP) — The leader of the University of Missouri is backtracking after blocking students who criticized his handling of the COVID-19 pandemic on Twitter. Spokesman Christian Basi on Thursday said system President and Columbia campus Chancellor Mun Choi unblocked the accounts Wednesday. Lawyer Chris Bennett warned he would sue if Choi didn’t unblock the students. Basi says some of the tweets were abusive and used expletives. But Bennett says others didn’t even directly criticize Choi.