If you used a point source (eg what you try to acheive by stopping the lens down as far as it goes) then you would be right. At small apertures, the angle from which light hits the sensor is limited, so the edge of the sensor receives light at a shallow angle where as the centre of the image receives it bang on, which is why we tend to see vignetting due to microlens performance (and sensor dust, as it now casts a more distinct shadow)
With a wide aperture light enters from many directions at once. The edge of the sensor not only gets light from an angle but also other angles too, reducing vignetting.
Personally, I think the argument for the f1.0 lens performing badly on a digital sensor is flawed. Yes, more light gets into the lens from the edges of the glass, but that doesn't mean it all strikes the sensor microlenses at an angle.
The question is probably how much extra angled light rays does the increased aperture give over the increased oblique light rays and is it noticeable?
Compared to a film camera would the image not just be darker for any given ISO generally (but this is true for all lenses?)
That is probably all complete tosh too, but at least I'm in good company posting here ;-)
