I think he got it right. Mossberg was one amongst a number of everyman tech columnists for a while, but Jobs really elevated him once Apple got popular.
This is exactly right. Most major (and many regional and local) newspapers had an Everyman tech columnist. Mossberg just happened to be that guy for the WSJ.
The other thing I maybe should've mentioned, though, was that Mossberg was a very early and emphatic booster of the Jobs 2.0-era Apple products. Back when Jobs had just returned after the Next acquisition, Mossberg got on that bandwagon immediately and began talking up their products.
So in its initial stages, the Jobs/Mossberg love-fest was a bit of a symbiosis. Recall that this was in a bygone era when the powerhouse WSJ at least as big of a deal as the struggling Apple Computer company. In later years, when Apple was the giant we now know and Jobs had ascended to the pantheon of industrial greats, the relationship probably did a lot more for Mossberg than it did for Jobs.
(It's hard to recall, but there was once a time when Apple was a niche, struggling little tech company with a minuscule market share, and big newspapers were still a Big Deal. The Jobs/Mossberg relationship had its roots in that era.)