This is unusual, isn't? Usually they don't comment on rumors.
Well it looks like they comment when there a blatant lie about them which can impacts the stock or impact sales, being more harmful than divulging confidential information, or being teased into making "no comment" being an admission of it being true because "otherwise they would have said it's false". That's always a balancing act.
They actually corrected Digital Foundry twice for their article which was not representing the PS4 memory layout correctly based on a dev leak. But it was really an honest mistake and a great source (I love DF, always). If I remember the sequence of event correctly, Sony sent them comments, and they posted their comments at the top of the article as updates. I suppose if you ask nicely... you don't get the dreaded "no comment"...