That phrase says nothing about root or xterm and I think you're being misleading by attempting to paraphrase it that way though I think I see how you got there. That's one possible interpretation of it (though not one Greenwald has backed), but it's equally possible, given the assertions of Snowden in the video with the article (which we now know to be true at least for phone calls), that it was an attempt to describe the experience of an analyst using such a system, requesting full access to a user's account, and getting it without interacting with google staff (after what delay we don't know), possibly without any legal paperwork other than making the request. We simply don't know enough details to be able to describe the process any better, we don't even know all the possible sources of intel for it.

Since Greenwald provided the sources for his statement and the article clearly indicates which quotes are attribution and which bits are commentary I didn't interpret it the way you did, and do think it's highly misleading to characterise this as a fundamental flaw in the article, or as something the guardian has 'walked back' - the guardian is not a monolithic entity and features content from all sorts of contradictory viewpoints. The writer wasn't clueless about technology necessarily - remember this sort of writing goes through many hands on the way to publication, and attempts to synthesise knowledge from various sources for a non-technical audience, while not revealing damaging details which could leave them open to prosecution. That process is going to result in text which is not as precise or illuminating as we or the writer would like.

So I'm all for correcting reporters like Greenwald where they over-reach or imply too much, and I do think he should have clarified this particular detail which has been left very vague, but we should clarify or correct, not attack and patronise, reporters who don't specify technical details, and bear in mind that technical questions of mechanism are not the only story here; there are far more important legal and ethical questions.