I believe that "those who forget history are bound to repeat it". With that in mind, instead cutting the problematic parts, I would add comment explaining why they are wrong. So they no longer could pretend the offense was "innocent" or that "they didn't know it was offensive".

It is like studying history without explaining the most disgusting parts like slavery or genocides. Having scenes like this help in situations where racist people try to claim that "it wasn't that bad". And would be even better if it was explicitly said in the film. (Like writing the explanation before and after the scene or in the lower part of the screen). Yes it was that bad and yes, we shouldn't forget or pretend it didn't happen.