Well as long as one keeps their mental rot within themselves, I don't see how its anyone's business. Thought policing is much more dangerous for society (and the children) than someone's private nonsense.
Drunk driving is not the right example. A vehicle is basically a weapon and society regulates whether you can use it or not. A computer and some software for personal consumption is much more private. Unless society decides that computer usage must be regulated and needs a license, comparing these 2 is wrong.
Understanding that people deal with some dysfunction or the other is the cost of living in a free society. Everyone struggles with some inner demons. Some much more than others. But we largely trust that they can keep these impulses in control. I don't advocate at all that we must empathise with those having this sort of disorder but we must allow people to deal with these issues privately.
Better, more vigilant policing is the answer. The impulse to stop crime from happening at the point it takes root in someone's mind is just the road to the worst kind of tyranny.
If he plays a race car game while drunk, yes, itβs ok, because is not real.
The same with the computer-generated images that look like children but they are not more real than the cars in the game