The blogger. It is customary at The Economist to assign to a columnist as a pseudonym the name of a foundational figure in whatever the column purports to be about ("Lexington" for their USA coverage, "Schumpeter" for the coverage of business, &c.). One person will write the column for a period, and then move on.
Babbage is the name of the Economist's Science & Tech blog, which this story was posted under. The blog name is being used to stand-in for the author's in that sentence.
Glenn Fleishman wrote this article, according to his tweets. (His twitter account is great fun to follow.) There are also other writers who post under the Babbage name.
Probably the author - though why they stated it like that I haven't a clue.
"About Babbage
In this blog, our correspondents report on the intersections between science, technology, culture and policy. The blog takes its name from Charles Babbage, a Victorian mathematician and engineer who designed a mechanical computer"
They do it that way because that's the way they do it. :-)
I've seen the use of "this Babbage" in contexts where e.g. the New York Times would say "this reporter". This would seem to acknowledge that there are multiple authors for these blogs; they can be identified by initials and location at the top of the piece. This one's author, "G.F.", is Glenn Fleishman of Seattle Times and TidBITS fame.