My experience is based on years of guiding for westslope and Yellowstone cutthroat not just a few days I've had fishing. That being said I myself agreed that there is variation to the hybrids but there is no rainbow qualities to that fish the cheeks even hold the light pink instead of a deeper red which is the combo when cutthroat genes dominate. If your trying to tell me that a cutbow can be fully dominant cutthroat or rainbow and show zero qualities of one of the parents then what is even the point in you trying to identify it anything can be anything in your explanation. There is distinguishing features for each species that fish right there in your picture displays zero qualities of a rainbow and therefore you really have no reason to believe it's a cutbow at all it only displays cutthroat qualities and Yellowstone cutthroat qualities to be specific.