Seems to me that the CRJ was waiting for a marshaller, in fact the person walking out may be him. So why then was the CRJ presumed to be clear of the TWY? Can the controller in charge of that patch see? Did the CRJ report he was waiting? Was any kind of local traffic passed? So many questions!
In my patch there are a few unsighted areas of the terminal area. And pilots often do fail to mention they're just sitting off the gate waiting. Hopefully a positive, in the form of tightened procedures, will come out of this.