Libertarians are the kind of people who think the regulation of interstate commerce degrades American society, while the unrestricted production and sale of scatological porn videos elevates it.
Any other barbs you'd like to trade?
As I said, if you want to ban it, then Amend the Constitution. As is, there is no specific power for them to do so.
Unless you are worried that they won't sell pr0n to Alabama but will sell it to New York? That would be a proper application of the Commerce Clause.