I'm not a consipiracy guy, or think that ISIS had anything to do with this. My gut tells me it was a crazy guy acting alone, and if the investigation draws that final conclusions and provides evidence to back it up, that's all most people are looking for... Show us how he got the stuff up there, show us how he did this on his own, take away all of the doubt and conspiracies and paint a clear picture of what happened.
I realize investigators made some very general statements a short while after the shooting, that they thought he acted alone, but that's certainly not a final conclusion.
If you think the investigators know he acted alone, and have dug nothing else up, why not come out and say that and show us the evidence that supports that?