Rusbridger moved on in 2015. Also whilst editor he was complicit in the smear campaign against Assange which the Guardian has been running since seeking refuge in the Ecuadorian embassy.
Ah, I didn't look up the author's credentials -- I will edit my comment. Often opinion pieces in newspapers are not the same as articles written by journalists and published as fully-fledged articles (usually they have an implicit caveat of "this is not the official opinion of $newspaper").