If you want members of scale to get support, while simultaneously keeping those support topics away from other members of scale then you need to use a group inbox for that purpose.
The scale_support group (or whatever you decide to call the team who supports scale) will have an inbox to receive messages. Those messages will only be visible to members of the support team plus the originator, which in this case would be the scale member.
The good news is that this is easy to set up with no additional categories.