I don't think it was Soros...mainly because he could have hired a more professional forger.
Not if the goal was to discredit the media.
I agree with your assessment of Soros. But isn't MO larger than just Soros? Aren't there more 527s than MO.org? It seems to me that there a lot of shadowy, emotional people who would be willing to do whatever it took to get Kerry in office. Soros is more careful than this, but isn't there a lot of other operatives out there assocated with 527s who are fanatically willing to pull something like this?