> So is there a path to an ethical, viable business model for the author?

Yes and no. An ethical business model for software in this world must be built on a long process of collecting good faith from customers, it just doesn't pay well enough compared to the ones that shatter said faith (adware, exploitation, dark patterns). I think the software moat will be more and more based on social capital. People are happy to pay for the software if they know for a fact that company/person behind it isn't being hostile to them. Look at Steam as an example of this. And you can always open source your code, and still make money through the means of good faith. Is it actually viable? I don't know. It depends on how much money you want to make.