
TANF (Temporary Assistance for Needy Families) is not ever being used as child support.
The TANF is only if the family qualifies for the TANF.
Welfare and child support are two entirely different things.
Even if one could claim that TANF was used for child support (which it is not) then there is still no justifiable reason not to give the poorest families the child support when it is collected, except that their needs are completely filled and the child support is just extra cash that is not really needed (which is true) and the child support system is a fraud - which it is.