Coworker thinks that I can't understand loss because I don't have kids

I rarely have anything worthwhile to post, but today I finally have a story:

Some coworkers and I were discussing the show Broadchurch, which came out a few years ago. I'd seen it and loved it, and this guy was just starting it (it's on Netflix). The show's arc is about a child in a small town being murdered, and how the family, police, and its residents react to it. It's really well done.

One of other coworkers (who has kids and has seen the show) walked by and heard us talking, and said to me (paraphrasing) "it's about a kid dying, and how it awful that is, but you hate kids, so why would you like it? it's about the heartbreak of a child's death. Was there a death of a cat in it? Maybe that's why you could empathize".

I was shocked, but I did have enough wit to reply that I wasn't some monster simply because I don't want kids. It doesn't mean that I'm dancing with glee about some fictional kid murder here. I've lost family members before. Am I totally incapable of understanding loss and heartache because I don't have children? Is that how parents see us? I could only "get it" if I imagined my cat dying instead of a child? Like, do they think that I'm watching the bereaved mother and thinking "why she's so sad? it was just a dumb kid"?

He said nothing and kept walking.