The regulation prohibits "messages encoded for the purpose of obscuring their meaning, except as otherwise provided herein" so if you and your friend made up your language to keep your communications obscured, then it seems that it would not be allowed.

If you happen to speak a language that's not commonly known in the area then that would likely be fine.

Aha. "for the purpose of..." Clears it up. Turns it into an argument about intent.

No white lies, hair splitting or exaggerating.

I think it is also important to understand the "no commercial business" part of it, too. That why the meaning is not to be "obscured", lest you mean to do business over amateur frequencies.

In short, if the traffic is encrypted, how would we know that, say, Verizon isn't off-loading traffic to amateur bands?

The way to think of it is that the FCC needs to monitor communication. (Possibly also other arms of the government.) If they can't eavesdrop, then that is an issue.