Congress in this instance has not made any law prohibiting a reporter from publishing a story, and reporters being required to testify is just one of a myriad of circumstances in which parties to controversies can be required to testify in one way or another.
If the freedom of the press is infringed, and the infringement was legal, that must mean Congress made a law infringing on the freedom of the press, right?
This is like arguing that reporters should be able to break into computers to get information for stories; after all, anything you did to criminalize that would be an infringement on the press.
I was disputing your claim that this wasn't a first amendment violation because Congress didn't make a relevant law. Now you're arguing that this wasn't a first amendment violation because there was no infringement on the freedom of the press, which is a much more tenable argument.
How was the freedom of the press infringed? I mean, the government requires that journalists and newspapers pay taxes, so is that another infringement?