From a D.C.-er intimately familiar with DOJ/judicial fights in the Senate:

1) there is no connection with the timing of the Stevens announcement – the Johnsen thing was probably planned weeks ago to get “buried” with a Friday afternoon release.
2) Personally, I think Johnsen has done a disservice to the President by not withdrawing before this – they NEED to fill that important slot and she has been nothing but a political albatross.
3) This will dishearten already disheartened lib groups – unlike their conservative counterparts during Republican White Houses, liberal legal interest groups do not have a seat at the table regarding judicial selection – Johnsen was really a big coup for them – gone.
4) The Johnsen ”journey” is the only way we stop extreme appointments – not with impotent threats of filibusters, but by raising the political stakes for Dem Senators in purple states. They don’t want to have to cast bad votes – make the vote go away. Johnsen was not beaten by a floor filibuster.