(The replies to the reporter's pinned tweet, meanwhile, are people gleeful about her messages being seized. I don't recommend reading them, except perhaps as a way of pondering whether a society where literally everyone feels encouraged to send sentence-long invective to literally everyone else has really done good things with communication.)
Note that what was used shouldn’t matter from the POV warrant vs no warrant. Follow on with: there is no claim that there was anything found in those emails. All we have is an acknowledgement that the government is undertaking warrantless surveillance of a reporter,. It doesn’t have to find anything, it just needs to be threatening enough to ensure that no one talks again.
Hence “chilling effect on journalism”
One would hope that serious whistleblowers would heed these instructions.
It doesn't matter how competent you are, if your blowing the whistle then you not want the slightest chance of making a mistake - got to be a high stress situation, someone holding your hand through a critical portion makes sense to me.