I don’t think you are wrong either. I just think that the word partisan might be too strong? Ideally, I’d like my judges neutral, but where do you find those nowadays right?
I think that’s a trick the right played on us, to convince us that we should be apolitical and stop us from getting politically organized.
The core belief system of the United States of America has always been to have fair and impartial judges. It's not a conspiracy theory from either side.
Having said that, either side would love to stack the court system in their favor, and the conservatives especially have been actively working on that for quite a while now.
As Americans, we shouldn't allow that to happen (FFS vote smart on judges!), either way. There's a reason why Justice is always shown with a scale.