The true and unjust reason the state is forcing this poor misguided fool to pay child support is this:
Follow the money.
If the father isn't forced to pay, the state through social services may have to spend to help the mother and child.
Actually, I think it's more like "Follow the DNA."
"Poor misguided fool" {imo... IDIOT} is no excuse - there are two innocent children's lives at stake. The donor was not anonymous.