As well intentioned as this is, remember the cardinal rule: NO GOOD DEED GOES UNPUNISHED.
I am willing to bet that most of these people will become lifelong welfare recipients, although in fairness, most Africans who come here are more productive and successful than the native black population here. But somehow I can't help but think that this will backfire and it will be you and me, the US taxpayer, who will foot the bill.
I'm willing to take your bet, but neither of us will ever know, will we? I simply don't subscribe to the "the U.S. saved my life so I'll repay the debt by going on welfare" thing.