They weren’t ignorant of pornography. They were knowledgeable men of the world. They were well aware of naked pictures that passed around in their day, but they still didn’t write against it.
If you got pornography banned, you’d find the Supremes would rule against the Bible as a rule of law. That’s how liberals think. When you ban something, the liberal will take that ban and apply everywhere including the Bible.
The naked pictures in the days of the founders were for not available to most people, first and foremost because of the cultural restrictions, but also because of the state of technology.
Whatever naked pictures they had then were as common as finding an 11-leaf clover.
Pornography these days is as available as the air you breathe.