According to the article, the cuckolded "dad" intends to keep seeing the child, and the mother's lawyer based his argument on the "existing paternal relationship".
If the man had reason to believe the mother did not know that the man was in fact not the real father, then he should have sought a declaration from the court, playing on the opposing attorney's argument, in order to get the court to answer the question: is he, or is he not, this child's father. (From a legal perspective, that is.) If so, he should demand all the rights accorded to a natural father (and accept the penalties), and if not, he should be allowed to walk away from the whole mess, or at least expose the court's hypocrisy and appeal, naturally.
[Beginning the super-rant portion of the post]
If, on the other hand, the man had reason to believe (and evidence) that the mother did in fact know that he was not the real father, he should sue the bitch* for fraud.
Of course, given the completely fucked up nature of the legal system, this all may be a pipe dream.
*Yes, I know. It's a nasty word. But frankly, convincing another falsely that they have brought a life into the world, leaving him, and forcing him to unwittingly pay to raise someone else's child [possibly making it too expensive for him to raise a child of his own], merits calling this creature an infinite variety of things far worse than the word "bitch" was ever meant to convey.
Survival of the fittest, you say? Perhaps. But by shedding every last bit of civilization and human respectability, this harpy-witch-creature has lowered herself to the realm of the animals, or beyond, and as she has rejected the boundaries that separate us from the animals, society and the legal system should refuse to continue protecting her. If it's pure, predatory, survival of the fittest she wants, then she should be prepared to accept its consequences.
Let he who has not convinced another falsely that they have brought a life into the world, cast the first stone.
1 141900 Mr. Excitement-Bar-Hum-Mal-Cha died in The Gnomish Mines on level 10 [max 12]. Killed by a bolt of lightning -