It depends on which way they are being defined, whether it is effective, and if it can be used later against those doing the defining...
At this point the current RCP averages (after ACA ruling) are rolling in the Romney direction (still show Obama ahead in the average but Romney is closing the gap and showing as the winner on more polls than he did just after the ACA ruling).
If they "define" him and yet the momentum continues to remain in his favor once the "correction" comes it will have a still larger effect. Also, with regard to the "vulture capitalism" if they let them to go all in on that one it will be fun to watch as they draw out first Obama's record (giving money to Swiss Companies, failing Solar companies, etc.) on his "crony capitalism" with the Stimulus as well as driving the point that his National Co-Chair made his money by doing exactly what Romney did. By holding for the right timing they can have better effect.
Basically, by waiting to see how the "defining" affects the campaign first they can better create a more effective answer to it in the future.