Nobody is being run out of a project over the slightest misstep; the first response to most issues will be communication, not bans. Bans from a project are the last resort, not the first. People who work in projects with codes of conduct don't go around afraid they're going to be booted.
Beyond that: what work do you need to do that you can't possibly accomplish without hurting people? It's really not hard.
In that case "be excellent to each other" should be more than enough.
"Explicit guidelines have demonstrated success in other projects and other areas of the kernel."
Many people do not start out sharing a common understanding on this topic. This HN thread is more than enough evidence for that. Hence writing down a framework to give people that common understanding.
You misread my comment rather heavily there. Codes of conduct are (one part of) a solution to a very real problem. There's no problem to be solved with "protecting 'political opinions' that hurt people", and even if there were it'd be far lower priority than people's lives.
And to answer your first sentence: people have learned to couch their intolerance in less blatant ways, but that doesn't make them less of an attack on other people's rights. People regularly think, incorrectly, that their discomfort is more important than other people's lives and rights. People push back, point-by-point, on each individual right or ability to exist and thrive in society. And most commonly (though not always), the people saying such things already have their own rights respected.
> Should people not be able to feel comfortable discussing such opinions outside of work or project spaces?
No, they most certainly should not. They should feel about as "comfortable" as people slinging around slurs and advocating segregation. That's nearly unthinkable today; there was a time when it wasn't. People's comfort "discussing" such things comes directly at the cost of the people they're hurting or advocating against. (And in any case, don't overestimate the weight due your opinion if you're not part of the group in question.)