Try another option.

In any workplace, conversations are held or comments made that are not work related and don't cause offence.

Greg's comments offended Mick - that's the difference.

This is an ok answer - but try another option for more perspective.

One of the reasonable steps his employer could have taken to prevent this problem would have been to raise and maintain awareness of unacceptable workplace behaviours.

Good answer.

It is widely known that racial comments in the workplace are unacceptable.

Many workers will say that banter becomes harassment when the behaviours become personal.