Are you saying none of them have any sort of political leaning in their judgment and legal interpretation?
No, of course not. But they aren't placed in their jobs by people with a specific political agenda, so judicial appointments tend not to be made based on such criteria.
I actually don't think your system is too far off being a really good idea, I'd just make it a stipulation that the only representatives who get to vote on a Presidential appointment to SCOTUS are those of the opposing party to the President, with an impartial oversight committee that determines whether nominations and rejections are reasonable. That way you're pretty much guaranteed to get middle of the road appointments.
