Message Censor was a feature added to interact with instant messaging applications before mobile phones and apps became common. It was used for MS messenger, ICQ and others. In addition to this, it could also be used to block offensive language from being posted on forums.
The Message Censor has been made redundant by the decline of the desktop messaging clients it was built for. The safeguarding functions and the evolution of Guardian web filter features has taken over the reporting functions that Message Censor initially was meant to handle.
While the service can still be used, the Guardian web filter and safeguarding will be able to achieve the same results.
In short, there is no need to configure the Message Censor currently and it will likely be deprecated in the future.