Iggy's investiture had the added disadvantage of coming just before the Christmas break. It meant that, with all the holiday distractions, he couldn't showcase himself.
Shorter Martin- nothing to see here, but it's a slow news cycle and I need my pay check.
Of course Ignatieff has been low key, and given the fact nobody gives a rats ass about politics over the holidays, it's entirely irrelevant. I suspect Ignatieff has been busy putting a team together and developing a strategy for the weeks ahead. The holidays are complete and utter down time, any attempt to secure some limelight or showcase, entirely marginal. People are distracted, the media on holidays, really the perfect occasion to do the quiet work needed, rather than appealing to universal indifference.