Dang

Probably knew it wasn't his kid. People in these comments seem to be about "mammals protect their young, dammit", but if it's someone else's young, and that someone else isn't around (even if that someone else is the same species) ...

Buffalos rarely leave their young unless it's hopeless. Most often the adults fight the predators.

I know it's a joke but with the caption "nature in a nutshell" makes it as though this is perfectly legit and plants the wrong idea to people that all animal species do this. Some species would instinctively leave their young but not buffaloes. Buffaloes rarely leave their young to predators unless they know it's totally hopeless to save them. This meme could have picked a more accurate species that does this escape tactic.

It seems like this joke is a recent perpetuation. I've seen in Reddit talk about it as well.

So they have something feel superior about, probably.