Perhaps it is because "ScriFre" doesn't roll off the tongue as well as "NaNoWriMo". That's why it's freaking me out.
ETA: Oooh! What if we start calling it "Scrifre", with the accent on the SCRI, pronounced "SKRI-free"? THAT WOULD BE CUTE. I can get behind it. It sounds like the name of a dog.