Santorum, sexism, and the memory hole

Rick Santorum wrote a commentary in January 2009 blaming fathers for their absence from their children's' lives:

There are as many reasons for this societal mayhem as there are statistics documenting it. At its core, however, is the irresponsibility of fathers.

Glenn Sacks organized a letter campaign against the entry and now it is gone; you'll notice that the links from Sacks's article get you a 404 from Philadelphia's servers.

I understand that websites are altered; they shift as html is replaced by java script, and as "web 2.0" is remonikered. But how easily should it be for a newspaper to hide its old articles?