I would argue that the existence of the HAP bit, along with the ridiculous amount of found security bugs (that on almost every ME currently in the wild will not ever be patched, mind you) can be seen as the ME being used as a planted NSA backdoor, disguised as being a (useful) utility.

They get to exploit all the bugs to do their nefarious things and can neuter the ME of their own machines to not provide the same attack surface. I find it highly unlikely that the NSA did not know about how insecure the current ME generation is and I also find it very hard to believe that Intel would not have put any effort into pentesting it.

Or maybe it was just pure corporate greed on Intel's part after all. I fear we'll never know, unless another NSA leak happens that contains information about this.