In this specific case I think there's even less reason to sue. As several of the articles pointed out, suing Think Secret -- and pointing out which articles contained their trade secrets -- actually confirmed the rumors. It's a rumor site. There is no confirmation of anything that's on it. If a particular rumor seems more believeable than others, it's because it's not disclosing anything a reasonably observant person wouldn't have already predicted.

Any site dedicated to discussing the future direction of a company, whether the source of the discussion is leaks, wishes, educated speculation or complete fantasy, can't be used to competetive advantage. If competitors change their strategy on unconfirmed reports from a rumor/leak site, they will react to false or inaccurate reports, too. If they only react to reports they believe to be credible, based on their own research, then they are setting strategy based on their own research.

To the extent that knowing Apple is planning a headless box represents a true competitive advantage, the lawsuit does more to confirm that report than the report itself. Case in point: I'm not a Mac guy, I don't normally follow Apple. If it had not been for the lawsuit stories, I wouldn't have ever seen the original report.

You can't fault someone for leaking a trade secret if it's not true. You also can't claim you didn't want the information leaked if it was an intentional falsehood designed to identify leaks.

If your characterization is correct, it seems like a decent practice to identify leaks. It seems like a terrible basis for prosecution.

And as for negative reinforcement, the defendant in this case isn't the leak. If they are pursuing litigation as a punishment, that's the very definition of a SLAPP case.