Its his issue and he needs to work on that. The problem already started by him projecting this insecurity into the relationship.

As of right now, it might not be a issue to you guys because you are still very fresh and in love. Once the glitter goes away and some struggles set in, he will however most likely use porn as a resource to avoid confrontation with you, where it matters.

Its speculation. Support him on stopping but if he is not taking serious approaches to stop, he is just talking about stopping and not actually doing anything.