When dealing with HR matters, sometimes you need to over-react to get ahead of the train.
For example, if a manager is racist.
You must be overly firm in your response this type of behaviour so as to set the right example at the top.
You must over-react or risk being seen as a hypocrite or not take unacceptable behaviour seriously.
But most times, its better not to over-react.
React quickly, but be fair in your response.