It's not surprising that Ron Paul would be against SOPA. That said, libertarians like Paul would have been against funding the projects that led to the Internet, and are today against funding similar government projects that might lead to future innovations. In many cases, innovations are bootstrapped by government funding or research, and then handed off to an appropriate role by the free market. Libertarians are us…
It's often assumed that without the ARPA the internet never would have existed. ARPA, however, is just one of many "internets" that sprung up over the years. There was also FIDOnet, Prodigy, BIX, Compuserve, MCInet, etc. Everyone with more than one computer thought to hook them together. Heck, even some friends of mine invented their own internet back in the 70's. If it wasn't ARPA, it would have been something else.
In contrast, the plans for ARPAnet were finished in 1968, and the system was operational in 1969. The concept was pretty pie in the sky at the time, and it's likely that the success of ARPA led to commercial implementations of packet-switched networks.
Additionally, the early private networks did not have the character of the "public Internet" which is a crucial component of the Internet we know and love today. Indeed, the reason we care about SOPA is that the public Internet, and not a patchwork of private internets, won the day.