would you call it a viewfinder
Yes: that's what it has. It's not 'technically not' a rangefinder camera, it's just 'not' a rangefinder camera.
I'd call it a folding viewfinder camera, or a folding camera with a reverse-Galilean viewfinder and front-element scale focusing. Not many of the Ricoh Six made, according to Camera-wiki.
My newest MF camera is a Yashica Mat LM, with a dead meter but otherwise in good condition. I've had it some weeks and not finished a film yet.