Bob Corker scuttled the union effort in Tennessee primarily because Conservatives are afraid of the domino effect sweeping through the South.
For all their talk about "government getting out of the way," Corker has proven that Conservatives do love government as a tool to destroy democracy and anything that is good for We the People. To Conservatives, VW is guilty of NOT stopping unionization efforts as "good businesses" do.
Democracy in the workplace or anywhere else threatens the power structure of Plutocracy so by utilizing extortion techniques ("Play the game the way we tell you to or we'll take the ball and play somewhere else!"), Corker proved that Conservatives have no interest in letting the private sector do what they want if it means that labor achieves more political power.