Recent (French) history tells us that this argument will probably not be taken into account by the law makers, because they are in majority incompetent, and more importantly this argument isn't backed with promises of positive income nor better behaviour. They will blindly look at the exposed pros and cons, and their limited expertise will merely say "so what" to these cons. The SOPA project, much like all Internet regulation projects, are considered as short-term "win-win" deals and long-term "win-don't care" deals with the Entertainment Majors. Since they expect the masses to not understand the cons either and keep voting the way they always did, they don't foresee any negative mid-term consequences either.

Arguments against Internet Regulation laws have to include profits for the government, otherwise I'm afraid the law makers will keep on not listening.