I think people are being slightly hyperbolic. It's basically stating that if a news outlet publishes unauthorized information then they won't be allowed access to the Pentagon. In general I think this is a good thing but not because I think it's a good idea. Rather, I think that the government, regardless of who happens to be in power, and the press should have an adversarial relationship, but the deep intertwining of the government and the press undermines this, even without corruption. You're generally going to be reluctant to frame entities that you have a positive relationship with in a negative way. And this agreement is essentially formalizing adversarialness.

I just have this feeling that in modern times if the Pentagon Papers were leaked to the NYTimes - but in the context of Ukraine, and especially if the previous administration was still in power, they very possibly might have instead alerted US intelligence instead of publishing them. WaPo repeatedly pat themselves on the back for playing a key role in tracking down the person who leaked the Pentagon documents in 2023. They mostly ignored what was leaked and instead framed everything as a story of tracking down the source and why he might do such a thing. We have a very broken media system, and this, probably unintentionally, might be a big first step in fixing it.