Not the OP, but all I see is a ham-fisted attempt by some writer at The Economist to try and whitewash the "credibility" of his ideological colleagues working

Not the OP, but all I see is a ham-fisted attempt by some writer at The Economist to try and whitewash the "credibility" of his ideological colleagues working for the Anglo intelligence agencies (there's a very high probability that both the writer and many of the people working for those intelligence agencies have attended the same schools and hold the same ideological views). It's a reversion to the mean of "ackchyually, they didn't really want to say that, and this is why". The percentage thing is just the scientist cherry on top.