I'm sure their "study" was bogus. It was just a humourous approach to the subject.
My cat loved showing up with a lizard or mouse tail dangling from her mouth. It was odd when she'd find a praying mantis. They'd stare at each other and the mantis would look like it was doing an eerie dance the way it swayed from side to side. I looked like a hypnosis session. My following cat was useless. We tried to get him to kill a tarantula, but he just stared at it. It made me wonder if it was a gender thing. I remember hearing that lions don't do as much hunting as lionesses.