NodeBB permissions are additive only, there are no negative permissions such as denying a specific user or group.
Sorry to bump an old topic; are there any plans to implement such a feature anyway? Or is there a way we can build this ourselves? Its a pain right now to organize birthday gifts and allow everyone but one person.
@whitts no... the title doesn't get injected. the code just takes the value of the title attribute from the <img> tag and displays it as a tool tip. you need to add the title attribute to the <img> tag with a value.