Why won't Wikileaks trend on Twitter?

Twitter is "censoring" discussion of Wikileaks by preventing it becoming a trending topic, writes blogger Bubbloy. As he points out with some neat research, the popularity of Wikileaks discussion far outstrips that of the pop culture ephemera that does trend. But is there a clue in the fact Twitter's feature isn't called 'popular topics?' Perhaps the #Wikileaks tag has already experienced so much chatter that it's become algorithmically unlikely to retrend. If so, perhaps a page for trending topic 'graduates' — or at least a limit on the algorithmic relevance of last year's spikes — would be nice.