I get the sense that it's not a mispelling in the sense that Ariadne doesn't know how kerfuffle is spelled. Maybe I'm reading too much into this, but I also think that the comparison to Ariadne's bunny plushie - i.e. a fluffy thing - is related. Kerfluffle can be read as a portmanteau of kerfuffle and fluffy - a kerfuffle caused by Lee's need for a soft, fluffy thing to protect his ego. Dunno. Deep exegesis that could be entirely off base - maybe it's just a typo.