The Muslim Public Affairs Council joined other Muslim groups in welcoming a decision by the New York Police Department this week to disband a controversial unit that spied on Muslims. Islamic groups have long protested the post-9/11 unit that kept records on the daily lives of Muslims and infiltrated mosques and student groups. Muslim leaders said disbanding the unit was a step in the right direction, but they expressed concern that the NYPD might start other discriminatory surveillance programs.