Suppose you were asked to write the script for a TV series on the Nuremberg Nazi trials. Hermann Göring was among those on trial. He was a leading Nazi, who held antisemitic views.
Like racism, antisemitism is an abomination, but as the writer of the show, should you be told that you cannot have Göring saying anything antisemitic?
Of course not: Such remarks would be quite consistent with his character. The same applies to Basil Fawlty.
He is a narrow-minded bigot, brilliantly played by John Cleese, and like it or not, that is his attraction as a character.
If he were mild-mannered and perfectly reasonable, where would the series be?