The meta analysis addresses porn in general. That includes fetishized content like violent or "taboo" pornography. It states there's no evidence that it makes sexual aggression more prevalent, and that population studies show that it's at least correlated with a reduction instead.
We can nitpick the wording all day long, but ultimately I think the takeaway is that there's no evidence that it has negative effects, and there's at least some evidence that suggests it has positive effects.
The inability to distinguish between selection and socialization means there's no evidence for a causal link. At best, it suggests that people who commit sexual aggression generally like porn featuring it more, but even that is apparently a weak correlation apparently.