I can tell you from personal knowledge and observation while serving on a senior level advisory committee (as a retired invitee consultant) that Mr. Hersh's findings and comments have been used by the services' intelligence communities as a point of begining for further inquiry and analysis. He has sources and means that have often been seen as one point of verification of suppositions and surmises by both current and human intell guys at these same agencies ( I can speak more assertively about current intell vis-a-vis human or strategic intelligence since that was my livelihood for a long time). His reports have been accepted as a source in papers written by students as part of their studies at the various senior professional military education courses. My personal experience was at the one I attended and I was told the same was true at the other services' senior PME schools.
I have been in the audience at an informal after-luncheon event attended by primarily field, and some flag level, intell officers at which Mr. Hersh was a speaker and panel member discussing subjects of interest to the group. It would seem doubtful to me that he would have been invited to participate, or that these attendees would have been there if Mr. Hersh had nothing to contribute.
I am aware of no reason to question his personal truthfulness or the same relating to his reports. Having been in that game for several years, it is absolutely true that there is a vast amount of usable intelligence information out there in totally open sources. All one need do is to reflect on novels like: "Clear and Present Danger," "The Hunt for Red October," and others of similar nature to confirm the accuracy of the above assertion.
His reports about the intial actions in Afghanistan were so absolutely bogus as to belong in the fiction section of your local library.
You can't defend them. Don't even try.
Why you're even here at this forum is puzzling.