Say what you will about George W. Bush as President: he has at least been a good ex-President. He hasn't interfered with his successor, and has stayed on the sidelines, unobtrusively.
Bill Clinton has been more of an activist, but has stuck to public speeches. He did speak out against W. during his two terms, but he also teamed up with Bush Senior in several projects, and hasn't directly interfered in, say, foreign policy.
Then we come to Jimmy Carter. It's hard to think of a worse example of an ex-President. He has often directly interfered with U.S. foreign policy. During the run-up to the First Gulf War he wrote to France and China to urge them not to support the U.S. Sent by Clinton as a negotiator to Haiti, he undermined our policy and made Clinton look foolish.
And now, he makes this comment, not in the U.S., but to the foreign press: "America has no functioning democracy at this moment." One might think, perhaps, that this statement is in response to Congressional stalemate. But no: it's actually in response to Snowden, whom he seems to think is some sort of hero.
One can only hope no one takes him seriously anymore.