Chop that's garbage.
The context was from a movie made in the 1950s and set in the 1800s.
There is no context in 2014 for referring to someone as an 'old darky'. None.
There's a massive difference to taking comments/jokes/whatever in old movies in the context of their time and cracking or repeating racist jokes on air in 2014.
They went through all this recently. They're both full time media professionals - it's not too much to expect that they could hold off on the racist cracks for a couple of hours and not broadcast them to thousands of people.
I think Johnno is channeling him...