One one hand, if jarjar is just a dumass, it means that palpatine's rise to power and the creation of the clone army are just the result of an impredictable blunder.
On the other hand, if he is indeed a sith, it means that his presence at the senate in ep. 2 was engineered from the start with palpatine (ie : having padme go back to naboo early in ep. 2, etc.).
As ****** as it may be, I think having jarjar as the ultimate villain just makes sense. If not, why did he appear in ep. 2 at all ??