Indeed. It astonishes me that Schneier continues to be taken seriously about (non-crypto) computer security when he has the same expertise in it as a typical NYT journalist.

I think the primary benefit that IAD, specifically the vulnerability research wing, has as being part of NSA is that vulnerability researchers rotate between SID and IAD as their careers progress, keeping IAD credible.

Your DHS idea would work (DHS already has a cybersecurity mandate) if there was a mandatory career rotation between NSA SID and DHS Cybersecurity. In my opinion there is so much overlap between IAD and Defense Information Security Agency (DISA) that what remained could be merged into DISA.