As far as how you would know if the particular colour character of the camera were removed, that would be the work of a custom camera profile, no?
That's sounds like it would work, but in practice with regards to improving workflow efficiency established with the intent of producing pleasing looking images, it doesn't consistently work. It helps a bit as long as the image isn't drastically changed as the viewer remembers the scene. Simon's flat, desaturated sample image he uses is not a desired starting point I'm interested in.
It's also disappointing to see he still uses sample images that don't represent typical shooting scenarios of most street/landscape photographers to demonstrate the advantages of scene referred processing/editing. I'ld like to see him start off with one of those HDR images like the "Cemetery Tree" only using a single properly exposed shot (which I've done a few that way shooting Raw and with better results) and see if you get consistent results from the less contrasty scene he used.
Why take 4 steps back in order to flat line an image as a way to establish some theoretical "scene referred" starting point. It just looks like more work than it's worth.
I actually applied a similar methodology with an Epson flatbed scanner in order to see all the available tonal differences that made up useable detail from shadows to highlights scanning negatives that Epson's Gamma curve driven under belly kept plugging up and blowing out.
I couldn't use a profiling target/software package at the time so instead used a colorful test image properly exposed to make the image generally flat and desaturated with its histogram end points pulled well back in order to give toe & shoulder room for the inevitable squash and stretch clipping behavior caused by tone mapping and restoring normal contrast. On some images this method allowed for a simple sigmoid or umbrella shaped curve to make it all look right but it still needed a lot of local contrast to bring out clarity.
It worked for some images but became a big PITA with others that had more or less contrast and brightness appearance caused by various lighting situations captured from scene to scene.
In the end it just became more work across a wide range of images than it was worth. The equation that's being left out of "scene referred" processing with regards to efficient workflows is that reality
has to be characterized as well, not just the camera's response, for getting consistent results.
If the defaults give contrasted results that hide detail, it's a lot easier to choose a Linear tone curve and/or set Contrast slider to zero than to turn everything off as a new default one size fits all that makes one image workable and the rest a PITA to edit.