He has another option, which corporations like to use. My wife works for a company that manufactures cheap chain saws, weed eaters, blowers and such stuff. Cheap power tools often break down, or cause accidents. They get sued for their crummy products from time to time. They offer little to no defense, sometimes settling, sometimes ignoring the issue, whatever seems right to them.
When they figure they've had enough heat, they change names, transfer ownership other members of the families, and other wierd crap. Working at the same plant with the same supervisors, the wife has signed paychecks from at least six different companies in the last 12 years.
So, this guy can just "give away" the rights to his script and/or software, and allow someone else to be the owner. He may or may not actually retain control, but he has "ceased and desisted" the distribution of that software. Facebook can't demand much more than that. He can change the name of the software, the name of the "owner", the place of business, and anything else he cares to change, as often as he likes, and thumb his nose at Facebook.