I'm not trying to win a legal case here, just sayin'... 1.
  "The broadcast industry does not want American's to
  know..." Opinion. Why would they want this widely known?
  2. "...legally obligated..." OK, that might be a little
  strong, but I stand by the POV that they can not encrypt
  this signal. The FCC citations (on Engadget article) make
  that clear (to me).

Agree. Sorry if I'm being pedantic, but this is really nothing more than the cable companies being compelled to broadcast these "mandatory carriage" channels without encryption and the impracticality of filtering every non-subscriber.

  It's possible that this works for me (and others)
  because... I am a subscriber to my cable company for
  telephone and internet access (but not TV), and so they
  can not send a tech out to disconnect me from their grid
  because it would terminate my current services[...]

That's why it works; however, it's not so much that they can't disconnect you but that they can't practically filter you.

  [...] AND they can not encrypt the Clear QAM signal for
  the Broadcast TV channels.

They can't encrypt but they can filter non-subscribers. If this were always practical, there's no doubt many companies would aggressively filter.

  Again, I'm not trying to argue some legal case here. But I
  do think it's more than just the cable company being lazy
  and not sending a technician out.

Sure, the impracticality is there but no legal impediments that I know of :)