Just to add...
It all changes when you get the original breeder's blessing for using a strain for breeding. Which doesn't always have to be explicit. Cannalope Haze from DNA Genetics (which I use) is sold with a description of it being suitable for breeding. Mr Nice seedbank maintains and breeds and sells strains also to keep that older healthy gene pool available for breeders (they mentioned it somewhere, it's partly what they are about). ACE seeds started selling 'breeder packs' since recently. There are more examples, and those basically come with an implicit blessing to use them for breeding projects. And once you've done the work that a breeding project entails...
Does that mean getting a breeder pack from ACE and CH from DNA and crossing the best phenos of those into F1, and selling those, is no longer unethical?
Towards the original breeders perhaps, but imo it still depends a lot on how you do it and what you work with. Simply crossing the best plants from two strains does not result in the best F1 or cross breed unless you're very lucky. But then it still requires some skill to even determine how lucky you were, or comparisons to the same cross but with different parents. Essentially, the least you can do is find the best matching pair, which aren't necessarily the plants with the most frosty and fattest buds. Or self the best females and run their offspring to see which female is most homozygous/stable. Even if you do that with just one of the lines for the eventual hybrid the resulting F1 will be a lot more stable.
And that's what the stud is about... mapping genotypes for multiple lines and plants is time consuming, so many stick to getting to know a male inside out, how it's trait inherit. For example, the taste of a good stud should generally be recessive and not completely dominant, else every cross based on is going to taste like it too. Genes to contribute positively to flower time, yield, structure, frost, etc, should generally inherit easily, be dominant. That also depends a lot on what you cross it with and your goals. In some cases (haze for haze hybrids, blueberry for blueberry hybrids) the opposite may be desired.
Cannalope Haze is according to icmag and thcfarmer a C99 knockoff. 8 week flowering short plants. Get a breeder pack from ACE (panama for example) and cross it with CH. Sell it. Ethical? In business ethics and breeding ethics? Maybe it is in such a specific case. Personally I think it still all comes down to whether you tried to create a quality product or just wanted to fill your pockets.
It also doesn't stop at that first pollen chuck if you manage to sell it, and then others get the same idea, possibly uses the same cross. Where does it end? At some point you'll be releasing new crosses just for the sake selling more beans. Not to contribute to the cannabis industry. At some point you'll be recreating crosses that already exist. Crossing with every new hyped elite cut. It becomes a mess exponentially.
Crossing two best phenos/keepers doesn't automatically lead to a strain. The result, unless stabilized first, is creating variety, the opposite of breeding a stable strain. Variety from which one could breed something new and stable, or find keepers to clone (and turn into elite cuts). If the pollen chucks would be labelled as what they are, pheno hunt packs or whatever, would the question of whether it's ethical still apply?