According to the New York Times, Sen. Joe Biden (D-Del.) said:

My question is, Is Justice Roberts going to be a Scalia, a Rehnquist or maybe a Kennedy? If I think he's going to be a Justice Scalia, who I like personally very much, I vote no. If I think he's going to be a Kennedy, I vote yes. If I think he's going to be a Rehnquist, I probably vote yes because it won't change anything.

I'm not sure I understand how this reasoning works. I can see why Sen. Biden might vote for a moderate conservative like Kennedy rather than for a solid conservative like Scalia or Rehnquist. But given that Scalia and Rehnquist are very near each other on their bottom lines -- Scalia is a little to the right of Rehnquist on a few things, and Rehnquist is a little to the right of Scalia on a few other things, but on balance they are very close -- why would Biden vote for another Rehnquist but not for another Scalia?

I can imagine some law-and-order hard-liners who might prefer Rehnquist to Scalia, since Scalia has on some occasions taken a broader view of some criminal procedure rights than Rehnquist has, and in cases in which Scalia's vote counted; in nearly all the criminal procedure cases where Scalia has voted to the right of Rehnquist, Rehnquist was not the swing vote. But I have no reason to think that Sen. Biden is bothered by Scalia because Scalia is too soft on crime.

Or is this just a "speak no ill of the dead" convention at work here? Yet surely that would have been as well served by just avoiding the Rehnquist comparison. So I'm pretty puzzled by this.