Well, they’re elected not appointed (except to fill a vacancy), “nonpartisan” elections, all 9 are elected statewide I guess, so yeah, they might all be rats.
This was only a 6-3 decision though.
I haven’t completely updated my list of officeholders since 2009. At the time, I had a breakdown for the WA Supreme Court as 2 Republicans, 4 Democrats and 3 “Non Partisans” (or couldn’t find affiliation).