But US is quite narcissistic about its political heritage, they would not let foreign inferior instructing them how to do legal stuff, maybe they will only accept foreign-born naturalized citizens.
You criticize the US for this, but I challenge you to name one government that appoints non-citizens to some of its highest government positions. This post makes me realize people will criticize the US for literally everything, even if it's something that every other nation does as well.
What the Democrats should do is announce as a block that Mitch McConnell has required them to filibuster any Republican nominee.
You do realize that will only aid Republican efforts to do away with the filibuster altogether and allow them to turn the tables on the Democrats by painting them as the obstructionists this time around, right?