It’s all unnamed sources and circumstantial, but it’s also very tightly woven threads that line up very clearly. Think of this like the initial reports about how Iraq 2 WMD stuff was all made up by the Bush Admin. There wasn’t hard evidence, but the manipulation was pretty easy to connect the dots on at the time. I doubt he can put names to sources without folks getting suicided, but it’s very solid analysis of how all the puzzle pieces fit together by a respected journo that has consistently been correct when doing these types of exposes.