I think the real threat to democracy comes from the response of the western governments to the leaking of the diplomatic cables.
By attacking Assange with claims that he has acted criminally in respect to his part in making the information public, the West (their governments) has effectively played in to the hands of China and those other countries that show no respect for democracy or individual freedoms. If Assange is arrested and jailed for his part in the leaks and western governments are complicit in helping the US take this action, what should the West's response be if some overseas Chinese dissident releases information that the Chinese government deems to be sensitive and say was obtained illegally and then requests the extradition of the dissident? How are they to respond to dissidents being arrested and jailed in China on trumped up charges, when the real motivation is to silence them? The West is in danger of ceding the high moral ground by their response to the leaks.
Rudd is correct when he says that the fault is with the US government for employing such lax security for what is very sensitive information, not with JA for helping disseminate the leaked documents. They should live with the consequences of their lax security and strive to fix the problems. Instead they are acting like the Chinese and legitimising that type of behaviour.