As I mentioned tony, this is not a discussion of man vs nature, we understand your position, and I agree with you on it. However, it was not about red goldens, only yellow golden or possible mutations despite whatever their derivation.
Yellow golden is a mutation, but like many cultivated mutations, changes can still occur to cause further mutation - liked (or disliked as in Tony's opinion) and visually enjoyed by many. As for peach, it may be a little unknown as to its actual origin, but it could be possible that yellow goldens are in its genetic background. There are many ways to get new colours. For example, salmon goldens are the combination of yellow goldens and dark throated goldens over more than one generation (F2 generation bred to itself to produce double copies of both mutations into a small percentage of offspring). Mahogany golden are said to be dark throated cinnamon goldens. I've heard speculation of cinnamon and yellow goldens used to produce peach (a theory I would be willing to attempt). Assuming the two mutations do not occupy the exact same spot in the genetic code, they can be combined. It would be interesting to know for sure what that combo would look like. The other mutations like silver and tangerine(not sure if any even exist any more) have fuzzy and speculative genetic history of rumours of cross species and multiple species breeding to accomplish this.