"The nuclear option is used in response to a filibuster or other dilatory tactic. A senator makes a point of order calling for an immediate vote on the measure before the body, outlining what circumstances allow for this. The presiding officer of the Senate, usually the vice president of the United States or the president pro tempore, makes a parliamentary ruling upholding the senator's point of order. "

In this context, it refers to the Republicans willingness to use any means to get their way. The Democrats wanted to stop bad judicial appointments: the Republicans wished to keep them from it. Now, the Republicans don't want the Democrats to try similar tactics.

"What's sauce for the goose...."