It's not really a tautology.

My whole point was to not criminalise porn itself, but handle the action within it criminally only if the action is a crime.

For example, choking someone consensually isn't a crime. Squirting isn't a crime. Having sex with your fake sister isn't a crime. However somehow, making porn of it, made these actions a crime. That's what needs to go. If the action in itself is a crime - murder, mutilation, CSAM, incestuous sex (yes, sexual contact with an immediate relative is a criminal act in the UK), these are all crimes, and if they appear in porn, they should be investigated and treated as such.

But, again, squirting isn't a crime. Drinking your piss, eating your partner's shit, (consensually) choking your partner, again, not a crime. So there's no need to criminalise their appearance in porn either.