It is news. The three criticisms the article raises are new and depend on their having gotten access to the spreadsheet.
Even though the author implies at the end that the Excel error is the least of the three, it's the perfect soundbite for a debate which, as you say, is political. Anyone can understand it (hey! I've made a mistake like that, those guys are as dumb as me) and in the symbolic language that governs such battles it's far more lethal than any substantive criticism could be [1]. Political hammer for a political nail.
