Apparently, Myrick is helping to promote a new book called Muslim Mafia, that's concerned about the "Islamizing" of America. Read the forward Myrick wrote for the book here. I'm going to look into this further. A terrorist intern would be a mighty fine way for terrorists to make inroads in federal government.
But a terrorist and a Muslim are two different things. I'm betting Myrick is mostly smearing Islam as a religion. Conservatives believe Islam is bad. If Myrick had respect for Muslims she'd be speaking in a more mature manner.
It also fits into the wingnut/birther conspiracy that Obama is a secret Muslim terrorist, who hates Christmas trees and is masterminding the makeover of the U.S. into a Muslim nation. I'm certain that this is what Glenn Beck and Sean Hannity believe. Not sure about Limbaugh.
The fact that this story is being heavily promoted on the incredibly slanted and biased Fox News, Human Events and in World Net Daily, the equivalent of Weekly World News (the paper that likes to put aliens on the cover), suggests that it's likely more wingnuttery.