It's more like don't harass people and then expect having a family will shield you from the repercussions.
These nastygram shakedowns deliberately cause personal stress to their victims (there is little other reason to send baseless legal demands), and so escalating the situation to be personally stressful for the attackers seems like an appropriate response.
As far as I can tell you're arguing that it's one thing to harass people during "business hours", but there is some greater principle whereby harassing them back at off hours is wrong because it might bother their personal associates.
If you don't want to get phone calls at inconvenient times either don't be a shithead in the first place (so that people calling you respect your schedule), or figure out how to silence your phones.
