A spokeswoman speaking to Bloomberg explained it as a matter of adaptation. Google has to update its policies to "reflect a constantly changing web," she said, and that means ensuring that people can "understand and see where their news online is coming from."
It's no secret as to why Google is implementing another measure to crack down on duplicitous news sites. The internet giant is under pressure from lawmakers and the public to do more in light of Russian attempts to influence the 2016 US presidential election, and culling sites that are deceptive by their very nature (not just their content) could be a significant help. The question is whether or not Google will be effective at spotting sites that hide their nation of origin. If it regularly waits until sites become news, pulling them will be more of a symbolic gesture than an effective deterrent.