That is somewhat similar to a possibility I suggested before in a different context, yes. But that doesn't have much to do with the point under discussion, which is that a creature which strongly resembles something well-known to most people is for that reason almost certainly ruled out as the MiTD. Even if we took the wizard's comment as meaning something like "this must be an entirely new species of X!", it wouldn't get us anywhere, because it wouldn't change the requirement that the majority of viewers have no better description than "IT".