Mythic thinking likes these big "North vs. South" abstractions. They're easier to remember and they make things tidy. When you really look closely, it's an awful lot more complicated than that. You run into ambitious politicians with their own agendas.
I suspect people are looking for a symbol of their own frustration or anger with Washington or "the Establishment" so they seize on the Confederate Battle Flag, which does make more of an impression than, say, the "Don't Tread on Me" banner. Having chosen the flag, they reinterpret history to justify their choice.
Please see my Post #90 - any 'reinterpretation' generally occurs on the side of the 'Union-at-all-costs' types...
;>)
A kid who's fed up with the uber PC mindset that too often afflicts the schools is not going to be too meticulous in researching the nuances of history when he looks for a symbol of opposition to a one-sided wilded. But to kids fed up with the system, a symbol of the heavy-headed establishment of the 1860s is an ironic choice for a symbol of rebellion against unfair authority.