Well, no it isn’t because white men have always had this ABILITY, that is to say, they have had the power or vantage point necessary to dismiss objections to violence by using the excuse of humor. The author is NOT saying that all white men do dismiss or mitigate objections (that would be sexist), just that they have always been in a position of power if they WANT to dismiss objections.

The fact that SOME white (and not very funny in most cases) comedians are defending racist jokes parallels the historical defense of violence and racism by people in power.