These kinds of resignations are interesting. The character is such a good protagonist, he resigns rather than do Bad Thing. But that pretty much guarantees the boss will hire someone more pliable. Why not instead swallow the pride and do Bad Thing but with some level of moderation? That would surely be a better outcome overall.
The argument is that it would destroy the character's honor or whatever. But that is also a kind of sacrifice for the greater good. Maybe a lot of those are in fact happening but just not visible.
> Why not instead swallow the pride and do Bad Thing but with some level of moderation?
A better answer is "refuse to do it without resigning". To begin with it gives you a better chance of preventing it, because maybe they back down, whereas if you do it or leave, someone does it. Then if they fire you, well, that's not really that much worse for you than resigning, but it's worse for them because now they're retaliating against someone for having ethical objections. How does that look in the media or in front of a jury? Which is all the more incentive for them to back down.
The problem with "well just do it a little bit" is that you can travel arbitrarily far in the wrong direction by taking one step at a time.
Dr John wrote a song about this dilemma, “Such a Night”