It's possible that sometime between "Angel One" and "Homeward," the Federation enacted a civilian law that was equivalent to Starfleet's General Order One, and the term "Prime Directive" may have been applied to both in vernacular usage because they'd be essentially the same thing. Perhaps the Angel One crisis even prompted UFP lawmakers to enact such a change. The 24th-century Starfleet is clearly much more extremist in its view of the PD than its 23rd-century equivalent was (even to the point of letting civilizations die rather than risk "damaging" them with contact, which is just insane), so that extremism could extend to the civilian culture as well, leading to the belief that a strict "hands-off" policy needed to be enacted for civilians as well. And that would be why, by the time of "Homeward," a civilian like Nikolai was subject to a law against contact with pre-warp civilizations.