Here's the deal. If you grew up in certain white neighborhoods in Milwaukee during the 1970s and 1980s you would encounter white people who said bad things about black people. One of the things they would say is that blacks just moved up here for welfare. They didn't have any evidence, mind you, it was just obvious.
But when Tommy Thompson first ran for governor he turned this racist urban legend into part of his platform.
Charlie Sykes, whose audience consists of not a few white flighters, has in the past raised the "welfare magnet" line. I cited this as an indicator he'll engage in race baiting and dog whistles in an exchange with Rick Esenberg at Shark and Shepherd.
There is ample evidence of folks moving up to Wisconsin for higher benefits. Read Jason DeParle's book The American Dream.
Instead I'll refer to what actual surveys demonstrated at the time: that higher benefits was not a leading cause for people moving to Wisconsin (as I noted nearly three years ago).