Rick Hasen at Election Law blog gives four reasons why "it would be rational" for Democrats to support Scalia for Chief Justice of the Supreme Court—

(1) Scalia would likely make a weak chief Justice. Scalia may be "one smart guy", but he is not a consensus builder. Far more than anyone else on the Court, his opinions (particularly his dissents) are caustic and nasty. He likely would not be effective in managing a cohesive conservative court.

Or he might be effective in getting the Court to produce more uniformly caustic and nasty opinions.

(2) Scalia, in his 60s, would have a shorter tenure as Chief Justice than a younger Chief who could have influence for a longer period, such as Justice Thomas or an outsider appointed to be chief.

Isn't there anybody older?

(3) Support for Scalia would allow Democrats to counter the charge that they would not vote for an anti-abortion candidate or a conservative, and they could make such a vote without changing the balance on this issue on the Court. Having approved a Chief Justice Scalia, Democrats would then have additional strength in the court of public opinion to oppose an ideological nominee to fill Scalia's old seat.

Why should the Democrats be concerned about a charge "that they would not vote for an anti-abortion candidate or a conservative"? They should be shouting it from the roof tops. Hasen is one of those guys who seem to think that going along with Republican bullies somehow makes them play nicer.

(4) To the extent Democrats could highlight Scalia's "ethics problems," so much the better for them.

The best place to highlight Scalia's "ethics problems" would be in the course of an impeachment trial.