To be sure its not an easy question, but we aren't starting from zero here.
Sure, "fair game", whatever, how can you "censor" a grassroots parody/mockery like this? Part of the game was, it wasn't actually stoppable in any meaningful fashion.
It seems rude, unethical, puerile even, to do this name-calling and dragging through the mud, if you will, and it was perpetrated/spearheaded, so to speak, by a journalist whose morals and platform encouraged that sort of tactic.
I don't think "censorship" was a solution to that incident, and since Mr. Santorum was a politician then "fair game" is a meaningless circumscription.
But perhaps the whole episode should reflect more on the character of the originator, rather than the target?