They banned it four days after the normal round of bans. I've understood "emergency ban" to mean any ban that occurs outside the normal review schedule.
Of course, the timing shows that they really could have banned it on time if they had been thinking ahead, so maybe it doesn't count for that reason, but if anything that makes things worse.
I kind of want to dig through the archives to find their articles from Mirrodin standard, both with the skullclamp ban and with the later "affinity is dead this time for sure" set of bans. I'm guessing that there will be a lot of promises that explain how they check and double check things now so that this can never happen again.
It's still amazing to me though that they let the combo get printed in the first place, given how obvious it was, and even more so that they didn't realize how combo-friendly an environment with poor instant speed removal and poor counterspells is.