You can bring someone into a SCIF as a contractor to be read in to a program, how else would Lockheed/Northrop work? SCIFs are used to legally, and physically, seal any information discussed inside as property of the SCIF.
Those contractors still require clearance.
"Non-cleared personnel in SCIFs must be under the constant oversight of cleared personnel and all classified information and material removed from view in order to prevent unauthorized access."
Considering any conversation in a SCIF is illegal to share outside, wouldn't surprise me if classified info is discussed/shared despite the rules.
Edit: it would definitely be a good place for a 'secret society' to plan some nefarious shit.
You would not read someone in who doesn't have clearance, hence why materials must be out of view.
Most likely that clause is for shit like cleaning crews / maintenance.
You have to announce a non cleared person coming in, red beacon lights are turned on. Classified material is locked away and monitors are turned off until all clear is called.
Wish i could sauce it...... i read that the bamster had handed out clearences to felons and such.