There are a dozen ways Fschmidt's comment fails. I'll address two of them:
(1) If the "welfare state" - whatever that term actually means, and whenever that era is supposed to have started - has caused black people to deteriorate into genetic inferiority, then the same degeneration should appear among those whites who use social services over the course of generations.
(It's possible Fschmidt will argue that "white trash" is equivalent. Because he's invested in his racism, however, he'll likely decide such whites are simply dysgenic outliers rather than the norm - a benefit of doubt he doesn't offer blacks.)
(2) Barring special circumstances such as mass exposure to high levels of radiation or to certain toxins, human evolution does not work that quickly: "Scientists estimate that the hominid lineage diverged from the ape lineage 5 to 8 million years ago. Homo sapiens, the species to which we belong, has existed for about 100,000 years." - (http://www.pbs.org/wgbh/evolution/library/faq/cat06.html)
Children learn how to make decisions from those closest to them. It's especially important that they're treated well during these formative years because parental negligence, incompetence, or abuse could all cause neurological changes in young kids whose brains are still rapidly developing. This is true for the whole of humanity, and not merely for certain races.
A family could exist on welfare for generations; relying on a monthly pittance from the government wouldn't do much, if anything, to their DNA. The contemptuous way they're treated as children, on the other hand...
(There is an exception of sorts concerning the genetic damage - "Polygamous Downs," for example - caused by interbreeding in closed communities. Most such communities, such as the FLDS, are white.)
