[notahacker]

Assuming the father is a living US citizen whose identity and whereabouts the mother knows, of course.

Either way, that doesn't really affect the argument that a BI payment supposed to be a minimum for one person to live off is unlikely to stretch to paying for the food, living space and private health insurance costs for another three, even if another parent's minimum payment is also being garnished to help.

The author's arguments you've cited essentially amount to the view that children of single parents should be punished for their parents' life decisions. It looks particularly crass in the context of accompanying arguments in favour of spending money on adults who choose to "idle away their time" and including those fortunate enough to be "already living off other people’s money".