It's really important to remember that there isn't an actual intelligence behind evolution. Finding your progeny cute and vulnerable is a huge evolutionary advantage. So specific traits are chosen for us to identify as 'young and vulnerable' markers. It makes sense that it's just a coincidence/side-effect that other young mammals have those same traits and we find them cute. Especially if those traits are exaggerated beyond what would be considered what is normal or healthy. (I mean look at those ungodly large dark eyes on that cute wittle wabbit - those would look freakish on a baby.)
I'll try to find it and post later but I remember reading this study about body proportions found attractive in woman. The study found that woman of a certain hip-to-waist ratio were the ideal, however when the woman's hip-to-waist ratio was skewed towards the ideal but even further to a point of being probably reproductively unhealthy men still found them attractive.
The evolutionary process even designs unideal physical traits. Such as eating, breathing, and communicating all through the same tube - or having our genitals right next-door to our waste disposal.
The lesson is to remember: evolution's only "goal" is to have you make as many babies as possible and to do as best you can to help them reach reproductive age and rinse and repeat. There's no intelligence behind it, and any seemingly elegant designs have literally millions of years of failures behind them.
[ Disclaimer: This is my first post so please don't go easy on me. ]
After reading a handful of comments I am surprised to see so many people think of what Eliezer did here as some sort of "bad" thing. Maybe I'm missing something but after reading all I saw was him convincing the man to continue the discourse even though he initially began to shy away from it.
Perhaps citing a theorem may have intimidated him a little, but in all fairness Eliezer did let him know at the outset that he worked in the field of Artificial Intelligence.