They are already selling ads, why would you think they wouldn't be raising revenue on the news side? Your argument that they wouldn't take money if it's not coming from the "core business" does not make sense economically. If your argument is that they wouldn't sell editorial selection of article topics, well, they did it publicly when they decided to report on the sale of a full page ad. Placement of articles on topics selected from the outside is usually far more discreet, with the proper PR firms mediating the selection, but the NYTimes is notorious for doing this.