Would we call it packing the court?
Instead, they are helping the judiciary cope with the level of cases coming through.
Similarly, republicans had the numbers in the senate when Obama was president to refuse him a choice, and they do now, to vote on a nomination. If they feel they aren't being hypocritical to deny a democrat a choice due to Kavanagh or whatever reason, surely Dems can change the law when they control the levers of govt. Similarly if republicans control the levers, they can add more/remove etc.
If I was a dem, I'd expand the judiciary, when I have the numbers.