Constitutional restrictions about "making no law" are about laws specifically targeted (in word or practice) at the group involved. Laws aims at everyone, even if they restrict those groups too, don't count. For example, some religions permit polygamous marriage. It would be unconstitutional for a law to say "Mormons can't have more than one wife" but it is constitutional to say "Nobody can have more than one wife". Similarly, a general law against anyone conspiring to leak national secrets is not unconstitutional even though it limits journalists as well as everyone else.
Beyond that, there is practical flexibility in the criminal system which does give journalists more freedom, even where they technically break minor laws in direct pursuit of their job but that can and should only go so far.
Again, if a journalist broke in to your office and stole your computer, hacked your medical records and stalked your children, you wouldn't want them to get off because they said they were working on a story about you.
The investigation into James Rosen's movements, by contrast, was tightly focused and actually involved actual search warrants approved by actual judges. Additionally, the aim of the investigation wasn't stop Rosen from doing his job, but to determine if he broke the law when he did it.
This isn't about Rosen's First Amendment rights at all, and the investigation into his activities is far more specific and far more respectful of his rights than the PATRIOT Act ever was for the rest of us.