StarSat already made clear how they intend to prevent easy access via the PIN and extra package etc. If a child ends up watching this, it means that their parents have left the TV tuned into the porn channels instead of "logging out" (kid could find the PIN too, but that's always a risk with anything PIN based)
Anyway, using a bit of logic, hopefully the judge realises that StarSat's protection is sound enough, and that it is the choice of adults to watch or not. Using the logic of this group, the next thing that should be banned is all violence and blood on TV, even on the news when all they are doing is presenting the news.
Lastly, if a kid wants to get hold of porn, they will find a way. Teens are already up to all sorts of shocking things like filming themselves doing it in public, posting slut lists and so on. Having access to porn behind a paywall isn't going to change that.
Worse comes to worse, kids can get their fix in the bible. Goodness knows there's already so much violence and sex in there...