Any thoughtful continuation of this subject requires us to get into the weeds: even doing just that is enough to attract heavy criticism.
When it comes to porn, the general consensus is that it must be based on consent. But even that is ambiguous: whose consent are we talking about? The actors, or the characters they portray?
It's very straightforward to require consent of each person filming. No matter what the story is, actors have human rights that must be actively preserved.
But what about the content itself? Porn that portrays fictional sexual assault is generally accepted as morally good. How? Audience.
A person may have a fantasy where they are the victim of assault. Are they doing anything wrong? No. It isn't wrong to be a victim, or to imagine it. From that perspective, the foundation of consent is met. An adult watching fictional assault porn can bring their own consent into the experience, reframing the content into a useful and healthy context.
But what if that person is not an adult? The general consensus is that a child cannot give consent. I think a better framing would be to say that an adult cannot ask for, accept, or use a child's consent. This rule is the foundation for making it criminal to sell porn to minors.
Many would argue that any fictional portrayal of a child being sexually assaulted cannot have a moral perspective or utility. A child might be able to fantasize as the victim of their own assault, but no adult can sell a fictional portrayal of that fantasy to them.
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So all that's left are the weeds: should a person watch fictional assault porn while imagining themselves as the perpetrator? Should fictional child sexual assault media be used as a pacifier for pedophiles?
These are hard ugly questions, and the emotional response from most people is an unequivocal, "no". Can we trust our emotions to lead to justice, or do they simply distract us with victory?