I think it's more complicated than that. They feel that Gruber is calling other people idiots, because they knew he was lying all along.
The college-educated liberal voter knows they are being lied to all the time and they approve of it.
Like this Gruber guy, they feel that most Americans aren't as smart as they and their college-educated circle of friends, so they need to be lied to for their own good.
The fact that they know the politicians they vote for are always lying makes them feel smarter and politically savvy. Almost like they're insiders on the game.
In the bizarro amoral mind of a liberal, voting for dishonest lying politicians is how you prove you're smart to the educated circle of amoral idiots you hang around with.