First, how are you sure it's correlation and not causation? Perhaps he's being driven to porn/developing the habit as self-medication?

Also, as to your previous point that it will lead to "harder" stuff, a recent study says no. Yes, there will be more opportunity and exploration of the topic, but that's something that will happen eventually to all individuals. It isn't studied very well, but at least this initial one says we don't naturally become more tolerant and require "harder" pornography over time. https://www.lehmiller.com/blog/2018/2/5/can-you-build-up-a-t...