Hi,
Sorry I didn't answer sooner. I wrote the Simple shape shader and to be honest I didn't understand exactly what was going on here until I had a chance to look into it more closely. The reason the colour isn't being redirected by the Redirect shader is that the Redirect shader only works with displacements. That's probably why it's in the Displacement shaders menu but not the Colour shaders one. To use the redirected displacement of the Simple shape shader as a colour mask as you are I think you will probably need to find a way of extracting the displacement with functions and converting it to a colour, however I'm struggling to see a way to do that which would work generally.
Looking at the image map shader I don't see how the colour of that could be redirected either. However someone mentioned it can be? If someone could post a clip with the colour of an image map shader being redirected by the Redirect shader I'd be interested to see it.
Regards,
Jo