Those are not exclusive; the charge is a constructive criticism, and in this case, it is not accurate. So I guess you could argue that any charge that turns out not to be true ceases to be constructive criticism, but you really seem to be arguing that making the claim was wrong, not that the claim itself was wrong.
And I seriously doubt that Bachus is part of this nefarious plot to stop Sarah Palin. He seems to really like her, and has said nice things about her.
Palin didn’t cause loss of the senate, so the claim itself was wrong.
Maybe “this nefarious plot to stop Sarah Palin” doesn’t really exist. Maybe the ruling class is supportive of Palin.
Maybe Bachus says things that are obviously attacks on Palin not because he wants to attack her, but because he thinks the words sound sort of musical rolling off his lips.