Probably have to point to general bias
Common characteristic to McVay's tree of head coaches are:
1) Young
2) Never had HC job in NFL
3) Offensive side of the ball, whether OC, QB Coach, Oline ( I don't count Staley as part of McVay's tree)
4) White Male
So a combo of: Offensive mind, with "Potential".. like drafting a high school player for the NBA.
If McVay can find a person of color to be a coach on the offensive side of the ball, then that could be a test for race bias.
Otherwise, people can argue that Raheem doesn't check off box #3 and #4. He's a "known" commodity vs someone untested with crazy new ideas.