No. NFL GM’s are not prejudice against black quarterbacks (QBs). In the last twenty years the NFL has made a lot of progress hiring African-American quarterbacks. Early in the 2017-18 season there were 18 black QBs and seven were their team's regular starter. There were eight until the Buffalo Bills benched Tyrod Taylor but that only lasted one game because Nathan Peterman was terrible. Almost one out of every four teams has a black QB.
Here’s just a few: Cam Newton was drafted first overall in 2011 and he won MVP in 2015. Robert Griffin III, won Offensive Rookie of the Year in 2012. Russell Wilson, won a Super Bowl in 2013. Jameis Winston, was the top overall pick in 2015. Dak Prescott set rookie records in 2016. Deshaun Watson set a record with 19 touchdown passes over his first seven NFL games. Black QB’s are playing at NFL levels and taking the game to new places.