You could argue that that's a focusing mechanism, not a requisite for a classification of viewfinder. It's still not TTL, and shows a larger area than the sensor sees.
It's not like a split prism is a requisite for a camera to be an SLR (not saying it shouldn't be, however ).
But a rangefinder camera is a camera that uses a rangefinder mechanism to achieve focus - it's got nothing to do with form factor or compositional method. Technically AF systems could be seen as a range finding device, but its more commonly used to refer to cameras which use a superimposed patch. It's incorrect to refer to the X100 as a rangefinder as its method of focusing is different to over 60 years worth of cameras classed as rangefinders. Just because it looks and functions like one doesn't mean that it is one: serious compact with a proper viewfinder is a more accurate way of describing it.