A federal judge declined to throw out a lawsuit filed by a man who alleges his age and race prompted the U.S. Department of Homeland Security to block him from working for a private firm that provides security services at federal facilities.In a written opinion, U.S. Magistrate Judge Young B. Kim of the Northern District of Illinois did not rule on the merits of plaintiff Derrick McCoy’s contention that Homeland Security acted with discriminatory motives when it determined he was not suitable for employment.But Kim …