So you actually believe that even in your ethical porn, all the women are there because they love the work, none are reliant on drugs to get through it, none will leave and then admit that they parroted the same stuff about loving their job but actually hated it and suffer PTSD as a result? You can't possibly believe that.
And yes, I think you absolutely can expect a partner to give up something they enjoy when that something is getting off to other women, and especially getting off to other women being degraded, humiliated and otherwise abused. I have met / been with men who consume a lot of porn which strongly affected their behaviour, but who wouldn't be at all happy if their female partners did the same, especially if them being degraded and humiliated then became their partner's sexual preference.
It's naive to think that this stuff doesn't negatively affect relationships (not all, sure, but many) and therefore asking someone to stop behaviour that impacts on you negatively is perfectly reasonable.
If the OP's partner was going to strip clubs frequently for lap dances, would it be more acceptable to ask him to stop? If he were using webcam services or prostitutes, would that be okay? There's an imaginary line being drawn here because the women aren't physically present or interacting with the men, and I don't think that line exists in reality - it's just what some have been conditioned to believe.