People added links to that page with the word "Santorum" in them. It isn't a link farm, it's a bunch of actual blogs and webpages whose owners are intentionally making this connection. It would be really impossible for Google to remove this result algorithmically.

Santorum's only appeal to Google might be that they have been abused as a political tool. Maybe the fear of distorted results plus some technicalities in the webmaster guidelines, might get them to change their minds.