a survey of 1,000 young people concluded that pornography can normalise sexual violence and harmful attitudes among children.

That’s irrelevant. This argument assumes that age verification laws will reduce children’s consumption of porn. The war on drugs has shown us that prohibition of this kind of stuff doesn’t reduce anything and only ever makes it worse. All that will happen is children (and adults) will now go to worse/less moderated websites which will on average have more CSAM and other real sexual abuse.