It’s not ideal as you have to set up and manage these other nodes, doubling your normal node count per qualification + 1 (the source with the LUT). If you have several qualifications that’s a lot of nodes all of a sudden!
What would be really clever is a relative scale, using the relative min-max of HSL values that are in the source image. This relative relationship could also preserve qualifications to an extent if the key source node grade changes slightly (if you are qualifying downstream of a correction for whatever reason, maybe a pre-clip group grade changes for example!). That would be very nifty! What do you think Peter!?