The problem is that “bastard” shames the offspring, not the people responsible. I don’t think any bastard child has ever had a choice to make in the matter. I don’t like the term at all.
We could call the male progenitor the “sperm-scatterer.”
It used to be that the parent/mother and her family were shamed as well, and that was an incentive to protect their daughters. Also, families cared about the offspring and NOT having them shamed with the brand of “bastard”.
Now we have “Generation B”, with children with married parents in the minority.