Yeah it's an issue of shared artistic goals, whether we're on the some page.
I doubt the player is trying to subvert the wife or retroactively change her personality, that's just how you see it, not how it is. Which is a problem with all art and shared artistic vision. People are going to have different views on things and if those views aren't compatible then there's no point in playing together.
If I was in the same position I might just ask 'So your wife is a strong willed woman and it seems like you're treating her as a servant, what do you think?'
The response might be 'Yeah you're kind of right.' Or maybe they try and correct you 'my conception of her character was that she has the same values as me, so it's not as if I'm controlling her as such.' Or maybe they just don't see what they're doing as controlling and this would raise some red flags to me about whether we're on the same page and compatible.
It's why the Bugbears and the wife are the same. You hit the nail on the head in the post where you say...
"OC oriented players often hate the idea that the GM has sole authority over the world beyond the PC, and they often
hate the idea that the player/PC can make a "wrong" moral choice"
The player treats the wife in a certain way and hates the idea that they can make a wrong moral choice. They expect their actions to produce results in line with what they expect. Being on the same page as to what those results are is the very core of OC play.
Or if moral choice is too restrictive then...
@The-Magic-Sword gets at the core issue.
On a systematic level I think OC play needs a way to determine why we're not on the same page. If it actually is irreconcilable differences about important things, we're done playing together. The best way to determine that is probably having a conversation about it but like a lot of roleplay stuff, that conversation has to be on the level of shared artistic appreciation. It's futile arguing about whether Black Widow would 'really' accept the PC's controlling behaviour or not (or whether it is really controlling and so on).