While I agree with you, I don't think Lieberman can be the first to use it effectively. CAIR and their terrorist associates will hammer him, accusing him of being anti-Muslim...and get away with it.
The first to use it is going to take a lot of heat. I think there's another FR thread reporting that Bush used the phrase -- I think he's the only one who could and not suffer politically. Once it's out there in the public, we'll hear more of it.
islamofascist has been in use for quite a while in venues such as Savage. Now it has appeared in public as islamic fascist in the very top office and that gives official sanction. Nazi is bad, but nazis are also fascist. The WW II Axis was fascist in its entirety, including Japan. We are back to that. islamist didn't catch on--too subtle.