Roberts and the entire Court surely have an eye on the confirmation. Keep in mind that O'Connor's opinions that justify stare decisis do so in large part to maintain public confidence in the Court's decisions and methodology. I have a feeling that 5-4 decisions will be held up at this point in time rather than issued.
The Court has to know that issuing a 5-4 decision now will be politically volatile, no matter which way the case turns, and would validate delaying tactics.
Whether the Court considers any of that is pure speculation on my part - but I think the projected ramifications of issuing a close decision are real.
I was of the impression that the court was in recess until February.