Currently, the product does not offer a solution to completely block/limit the access of the MMC client to a specific Active Roles server. It is possible to limit the access to certain Active Roles MMC consoles as described in the article below; however the service will still be accessible if the Active Roles Server's instance name is used.
See this article for: Removing ActiveRoles Servers from the 'Connect To' dialog during launch of MMC (102445)
An enhancement request TF00789157 has been created detailing the feature above.
The product team will evaluate the request and this feature may become available on a future release of the product.
Please refer to this article for updates or contact support referencing the Enhancement Request ID: TF00789157.