Stabenow will win reelection.
James is a black conservative, like Darryl Glenn (CO-SEN 2016), that upsets liberals.
Black liberals will despise him when they find out he is married to a white woman, despite black liberals' hypocrisy of "tolerance and acceptance", a black man marrying a white woman especially when that black man is a conservative a la Clarence Thomas is seen as "deep in the sunken place".
As a black person myself, I have to say that you are correct about this. Many blacks (like many whites), especially older ones, have a negative view about interracial marriages. My own father and uncle, for example, consider it to be a "betrayal to our race", given the history of this country. So that very well could be a factor with black voters in Michigan.