I don’t think Republicans ever said they “couldn’t” change the rules. Especially since they previously threatened to evoke the Nuclear Option under W.Bush to get judges appointed. Republicans said, referring to the complaints made by Democrats, that they “shouldn’t”. Of course Democrats did and set a new Precedent. Democrats opened the bottle and let the genie out. It was the wrong thing to do but its not going back in just because they hold the short stick now.