You are accusing the black student of being "humourless" for  reacting so vehemently to a joke about the "lash" and a "master"?
Of course, Massey should not have automatically caved to the students' demands. And it appears Marrus has a long and distinguished academic record, and should not be judged on one out-of-character incident.
However, it is not hard to understand why black people get so upset about incidents like this when people like you still -- in 2017 -- think centuries of slavery, lynching and lashing is worth a laugh.