They (the left) say those things 1)because they aren't smart enough to think of something origninal, and 2)because they feel a real threat to their liberal ideals.
From what I've read so far about the Muslim Brotherhood, they are not extremists. And the article says he likened one aspect of the Tea Party to one aspect of the Muslim Brotherhood. Your insinuation is runt-of-the-litter strong.
Muslim Brotherhood Breeds top Al-Qaida leaders, as well as the entire Hamas organization. They get credit for not <i>directly</i> blowing anyone up for 40 years (a major accomplishment for a Muslim organization, I know), but that's about it. Overall they're about as moderate as the Aryan Brotherhood.
Shit, based on that criteria the US is the Great Satan it's called; our "indirect" lethal meddling is well documented. Not sure the world would be worse off with the MB in charge of Egypt. Anyway, that's not how they're described today in wikipedia, though historically I see some crazy stuff. Like us.