I don't think that design was for fuzzles at all in the first place. He may have just saw oppurtunity later on or something. I would have changed the design for a fleech around also, a small ugly thing like what was drawn before would suck. Except for the "piss out of head" super-power
Of course, since Alf assures us that Fleeches are perfectly natural Oddworld creatures, we could theorise that the Fuzzle-like production image it was Fleeches looked like in the wild, before they were all captured and altered to be pets. Perhaps Fuzzles and Fleeches, since they look similar, are quite close on the evolutionary side of things.
He's talking about the pre-Fleech pictures, they show a Fleech with a spray of poison/water/something coming out of it. Mr Mac wonders why neither Fleeches or Fuzzles had this feature in the end.