Well, it's obvious that the Witcher 2 anniversary is too simple an answer. So we must delve deeper into the mystery, and ask why that was the chosen release date...
Perhaps the Administrator is a closet Norwegian, and wishes to celebrate his National Day?
Perhaps he is a British patriot, and wishes to celebrate the Relief of Mafeing?
But no, none of this fits the sombre and cynical mood of The Witcher.
So I'll say that the date was chosen to commermorate the Fall of Jerusalem to the Persians in 614AD.