I never said they don't. Simply that in this case there is no evidence, direct or circumstantial, pointing to Intel ME being born out of an order by an intelligence agency. Could it be? Sure. But critical thinking demands facts, not speculation. Facts are:
1. Intelligence agencies have been known to force companies to give them access to their products.
2. Companies have been known to comply, if reluctantly, at least until a whistleblower exposes the program.
3. Intel ME was developed as an on-chip version of an external card that is actually useful.
4. Intel has made poorly engineered products before.
5. Intel isn't in a habit of open sourcing firmware.
6. From a technical standpoint, Intel is fully capable of creating a system that doesn't allow C&C through a bug and an exploit.
7. AMD, the second largest computer chip maker does not have a matching system that can't be disabled and that has similar bugs.
Based on this, I'd say it's possible that the NSA (or equivalent) asked Intel to develop ME and add a bug to allow C&C, but very unlikely.
It's also possible that the NSA (or equivalent) asked Intel to develop ME and add C&C and Intel did it through a deliberate bug, but very unlikely.
It's also possible that Intel tried to develop a feature the market might want, and screwed up the implementation. This seems to me to be very likely. It's the simplest explanation (Occam's razor) and it requires only incompetence, not malice (Hanlan's razor), so it's sort of by default most likely.
If someone can produce an iota of evidence to the contrary I will change my allocation of probabilities appropriately, but so far the evidence is "it could have been done" and "they've been known to spy on people in the past". In my book that's not a strong enough argument.