But the originator of the explanation did have the second question in mind. From Wikipedia:

As evidence, Lorenz noted that humans react more positively to animals that resemble infants—with big eyes, big heads, shortened noses, etc.—than to animals that do not.

Unfortunately Lorenz's original article is not available on the Internet, but I'm guessing that he was aware that some people find certain animals cuter than infants, but given the superstimulus and perhaps other explanations, did not consider it fatal to his theory.