[jlokier]

The assumption comes from this:

> If she is resorting to sex work to feed her son, what is she spending the father's child support money on?

That implies:

(a) there is father's child support (a sweeping assumption that is often wrong), and

(b) the father's child support is sufficient by itself to feed her son without needing to resort to sex work.

It's also suggesting that the mother is misusing funds somehow.

The distinction between "feeding" and "raising" you might have picked on would be, in my view, a quibble over a technicality. Child support is to contribute to the costs of raising a child, it's not earmarked to specifically cover food, and if you need extra income to raise a child, it's acceptable common language to phrase that as earning money to feed a child.