Fredo is a derogatory ethnic slur for a dumb Italian. It is similar, but worse than calling the Mexicans Pedro or the Chinese Hop Sing or Native Americans Pocahontas. Those slurs don't even imply a dumb person but they are still derogatory toward a particular race. By definition that is racist. It is not necessarily bigoted, but it is definitely an ethnic slur.
Rush Limbaugh was the one who started referring to Chris Cuomo as "Fredo", which his rabid white nationalist audience picked up on. One of his fanboys actually crashed a Cuomo family gathering and called him Fredo, then pretended that he actually thought that was his name. In that case, it was intended as a bigoted racial slur because the Alt-Right hates Chris Cuomo and CNN the same way the White Supremacists hate Blacks and Jews. Putin, Drumpf and Murdoch have the Alt-Right convinced that the Fake News Media is the Enemy of the People because they are nothing but a bunch of stinking whistle blowers who are obstacles to their dictatorship.