Millions of insects, slugs and small rodents are killed every year to protect crops, animal feed and food production no matter one's diet (eating is necessary for survival as far as I'm aware, humans haven't figured out photosynthesis yet), so it just gets even more ridiculous as a moral or ethical conundrum. Both parties here have no idea what they're talking about. Talking about livestock animals would've been a better argument, as one can survive without killing them.
Though I agree with the idea that you should not kill things for fun, of course.