I don't think that Johnson would like to see his case used as club to hammer the first Black president of the United States. SI am amazed to see that Senator McCain is introducing this idea to pardon Johnson after all this time. I agree Johnson deserves a pardon...it is clearly an injustice done to the man and i don't care that Johnson has long been dead. He should be pardoned. I just don't think McCain is being altruistic in his motives. I don't trust "that one". He says that it's not meant to cause Obama any problems or to criticize him because the President is busy,, but it still seems like to me a ploy.
This article mentions a Kenneth Burns documentary on Jack Johnson's life. I've embedded it below
McCain Asks Obama to Pardon Boxer Jack Johnson