The only one to whom that was ever attributed was a Klemperer, IIRC. He’d had plenty of previous experience playing Nazis in Hollywood (most famously in Judgment in Nuremberg) and was very alarmed when he went to the audition for Hogan’s Heroes and realized that it was meant to be a comedy. At the time he described the show as a workplace comedy that could have just as easily taken place at General Motors.

Interestingly, if you’ve seen the pilot you’ll notice that Larry Hovis, who plays Carter, is actually a one-off character and instead the main gang includes a tailor named Vladimir Minsk. He never showed up again after the pilot, and that’s because Leonid Kinskey, who played him, was also Jewish and was so disturbed by the concept of a comedy with Nazis that he walked. (Kinskey is probably most famous for playing Sascha the bartender in Casablanca and was also a refugee from the Nazis.)