Sorry - but if true, he's now in way too deep. If false, no "Gotcha" bounce from the story.How do you figure he's in way to deep? There are plenty of ways to play this card for a good gotcha bounce.
For now, he's doing what a good candidate should do, setting his agenda and avoiding distractions.
If this issue starts to affect his target voters he will spring the trap. Not until then.
This sounds like a new form of strategery to deal with one of the many Obama controversies, which he has yet to excercise against the many other damaging stories that have actually proven to be of substance.
The closest example would be the Rathergate smear against Bush which was quickly and decisively destroyed by the blogosphere - how ironic in light of your statement.