It might be correlated to journals that charge $70.00 per paper. If the NYT publishes a story citing a journal, the journal may go back, see that the NYT never actually bought the paper and a journalist just got a copy from somewhere, and then try to sue the NYT. The 'study' may be a weasel word that is used to avoid this outcome. And yes, over one article this is frivolous, but if the journal waits a few years and amasses 100 instances where this happened, then the NYT may actually go to court.
That's definitely not the case... Journals provide news outlets with complimentary copies of papers specifically so that they can be written about. Often, but not always, they're even provided in advance of official publication.
