FWIW, I interpreted the proposal more as an attempt to improve lower Bald Eagle Creek, rather than improve Spring Creek in any meaningful way.
Spring Creek doesn't need any help (in terms of population management, it does need protection in terms of flow rates and water quality). That said, it can handle a removal of some fish, while maintaining STRONG populations. Whatever % are lost would be replaced in short order, as reproduction is extraordinarily strong there.
As such, making sure the culling is even is not really important. What would be important is taking enough fish to take an honest shot at seeding a more genetically suited population elsewhere in the drainage. As I said, I believe the likelihood of success is relatively low. But success would be huge, both for this drainage as well as making roadmap for how to do it elsewhere in the state. And the trade-off is low as well. You can take a sizable number of smallish trout from Spring Creek without much in the way of ill-effects at all. It's the perfect place for such a trial.
And I do think such efforts would succeed sometimes. In cases where habitat is suitable, but genetically inferior PFBC strains have caught on to only a limited degree. Mix in some wild DNA from the same drainage and the success may increase substantially.
Even if such trials were met with a low success rate, it's a huge potential reward (a new thriving wild fishery) for a relatively low cost and effort. Do the transplant once or twice, and that's it, you have a self sustaining fishery for eternity.