This greatly exaggerates the hazard of riding it.

Yes, it's possible, but in the real world spokes break all the time and wheels don't taco because of it. When spokes break and wheels taco, it's usually a simultaneous and not cause and effect, but both happening from the same cause.

Odds are the rim will stay true enough for you to ride home on it, with the brake QR opened so it doesn't rub. You might also consider carrying a spoke wrench so you could bring the rim a bit truer in the field. The only safety step I suggest is that if you're riding any distance with the loose spoke, twist it around it's neighbor so it can't get tangled in anything.