LOS ANGELES—A man who sued the Montebello Unified School District (MUSD) and a former superintendent—alleging the schools chief lured him into a sexual relationship earlier this year with promises of money, training, and help in getting his U.S. citizenship—will have to shore up his complaint for it to proceed, a judge ruled Monday. Los Angeles Superior Court Judge Maurice A. Leiter found that attorneys for plaintiff Walther Medina had not shown in their current court papers that the alleged actions of then-MUSD Superintendent Anthony Martinez were foreseeable on the district’s part and occurred during the course and scope of Martinez’s employment. The judge also found that Medina’s claims for gender violence and a violation of the state Education Code were not fully developed. Medina’s lawyers were given 30 days to file an amended complaint. MUSD lawyers maintain in their court papers that any alleged relationship between Medina and Martinez was …