Let me start by saying I agree with those who say it makes no sense to seriously consider impeachment now. But I disagree with those who claim Palin's argument is extreme. Almost every argument from conservatives I've seen in response to Palin's call for impeachment is that it would be political suicide. It would. That's why it makes no sense for Republicans to actively pursue it.
But something being politically ill-advised doesn't make it extreme. Ted Cruz and Ron Johnson held essentially the same positions on policy during the shutdown debate. The sharp disagreement was over strategy. Pursuing impeachment now would be political insanity. But came the same be said for Republicans stating that the President may be guilty of impeachable offenses? At its essence, what's the point of Boehner's House lawsuit against the administration? That the administration is flaunting the Constitution; is't that potentially impeachable?
I suppose you can argue Palin's strategy is extreme. Her overall position is not.