I disagree. I recall favoring the majority threshold when Republicans were in power (for nominees) and the 60-vote threshold for legislation.
I want to say that on rare occasions when liberal nominees are defeated it’s because they have lost the PR war. Conservatives are the ones who don’t get the up-or-down vote.
It should not be the Majority Leader’s choice to set the bar. Back in the day, it took 2/3 vote to get the Democrat presidential nomination. It took a 2/3 vote of the convention to overturn that rule. (It happened in 1948 as I recall).
Also back in the day it required a 2/3 vote to reduce the cloture rule to 60 votes. In 1975, the Senate voted by a 2/3 margin to reduce cloture from 2/3 to 3/5.
Now under Robert’s Rules (which the Senate does not operate under), a rule cannot be suspended without the consent of the minority larger than it is designed to protect. (That is, the cloture rule should have required a 3/5 vote to exempt nominees from the filibuster rule. So far as I can figure it received only majority consent.
But now that we have it, it should stay that way. It’s not fair to have a lower standard for Democrat nominees and a higher standard for conservative nominees.