Yes! I think we tend to get caught up on the whole "John did something to Arthur" that we forget there was a third party in the room who set it all up very intentionally while John was in a deeply vulnerable and altered state. Kayne wasn't John's partner in crime, he was manipulating and exploiting him because he knew that in any other circumstances John would've been horrified--and that's what made it fun for Kayne.
And like... the same can apply to Arthur with Faust and John. Arthur was forced to commit an incredibly violating act that was violating for both parties and on some level due to in this case biological need he did enjoy it. But Arthur is a victim there too, it was a violation against him as well and any resulting pleasure made him feel worse about it. The violation of being forced to incredibly intimate violence (fingers in Faust's eyes while pinning him down with his body), of forced cannibalism, of repeatedly harming and overriding the autonomy of his friend in order to eat. Theoretically, it was all Arthur's choice. But we rightly blame the architect of the situation, the KiY.
And that point about John being so new is important, while there's not a lot of external material survival pressure the same way starvation works for humans, John was clearly emotionally in a not so dissimilar a survival state and he lacked the experience to navigate it alone in even normal circumstances, let alone in the Dark World which explicitly heightens emotions of hurt and fear and anger while Kayne was actively provoking him to make him worse.
There's also the fact that John tends not to identify with his own body. Arthur's body is their body. Maybe John is inhabiting the vessel of Hastur to inflict violence on Arthur's body, but it's implicitly violence on the body John identifies with even if in Hastur he's interacting with it externally. So there's that as well, that every act against an Arthur was like an act of self-harm, a violation against his home, or a violation of the pact between Arthur and John which John hinges his safety and wellbeing and very identity on. A lot of John's freak-outs in S4 are directly a result of him feeling insecure and unsafe in Arthur's body not due to Arthur but as a direct result of his actions in the Dark World because that mutual agreement between them had been so severely abused that he could no longer trust it. We've joked about how the bone cathedral was Kayne setting up the divorce to end all divorces, but it really was Kayne taking advantage of John's horrific position to intentionally destroy his sense of home and security in Arthur.