"A Supreme Court decision that concessions of this sort were unconstitutional would have taken them off the table and actually increased the effective sovereignty of elected officials"

This quote by Michael Kinsley is referring to the power of the Supreme Court to make decisions that can affect the sovereignty of elected officials. He is recommending that if the Supreme Court were to make a decision that specific concessions were unconstitutional, it would take those concessions off the table and increase the efficient sovereignty of chosen authorities. This would imply that elected officials would have more power and authority to make choices without needing to stress over specific concessions that may have been formerly available. This would likewise indicate that elected authorities would have more control over the choices they make and the laws they pass. In essence, the Supreme Court would be increasing the power of chosen officials by removing particular concessions that may have been formerly offered.