I realize that the title here is what Google put on their blog, but it seems to me that "detrust" would be more accurate than "distrust".
“distrust” alone only communicates not trusting, true. But the word isn't alone, it is in the phrase “plan to distrust”, which communicates that the not-trusting is a change from the status quo that will occur in the future.
Not necessarily. "Plan to distrust" would be consistent with "a company has announced that they're going to start issuing certificates; we won't trust them". You and I know that Symantec is a major CA which is currently trusted by Chrome, but that isn't implied by the headline.
http://legaltimes.typepad.com/files/garner-transcripts-1.pdf