I think they are using Pickering to prick the Lott bubble, to disarm and defuse the old Democratic civil rights/racial politics machine currently clanking back into action. That is, the Bushies expect to win on Pickering, not lose. The case that Lott had expressed unacceptable segregationist longings was strong, after all. The case against Pickering is weak. What better place for the Republicans to make a stand?
Of course, the Bush Administration should really be confusing its opponents by nominating "wedge" candidates who'll split the liberal coalition: pro-choice, pro-gun, tough-on-crime but strong-on-civil-liberties candidates like, say, Boston University law professor Randy Barnett.
And I have their ultimate Supreme Court pick -- but I'll save his name for later.