This is the second of a two-part column. The first part was published on Monday.After ruling that a professional services exclusion did not excuse Sentinel Insurance Co. from defending Walsh Construction Co. against a wrongful-death claim, U.S. District Judge Jorge A. Alonso considered whether Illinois estoppel rules blocked Sentinel from asserting several policy defenses.Monday’s Trial Notebook focused on Alonso’s analysis of Sentinel’s duty to defend.On a construction project where Walsh was general …