Garfield would seem to have three strikes against him in our current climate. Prior is gay, American and a WASP; Garfield is straight, British and Jewish.
Newman played a Jew in Exodus, but that might have been it. His performance as the Irish lawyer in search of redemption in The Verdict is widely regarded as his best. I couldn't imagine anyone complaining about his casting over ethnic authenticity. Ditto Jason Robards for his many performances in the plays of Eugene O'Neill, most of which still cast a shadow over others who play the roles.
I realize that Sarah Silverman is specifically talking about the misrepresentation of Jewish women in current culture, but it wasn't too long ago that Nathalie Portman played our only Catholic First Lady in an acclaimed film performance, and it wasn't too long before that that Jessica Hecht and Scarlett Johansson played the Italians Beatrice and Catherine in an outstanding Broadway revival of A View From The Bridge (alongside Liev Schreiber, Corey Stoll and Morgan Spector).