Wow... so many different thoughts go through my mind.
First, IIRC, many serial killers and the like started on small animals before they worked their way up. Not that there's a cause/effect thing going on, but I'd mark them for close future scrutiny.
Second, it most likely is a power thing, just like rape isn't about sex. Most likely they've got an SSI (Sh!tty Self-Image), and this makes them feel more powerful. I don't know that being thrust back into their place (much as I'd like to do it) would help offset that...
Third, I'll take the midnight to two beating shift...
Fourth, there are two kinds of power or authority: positional and earned. They *are* higher on the food chain, so to speak, than that kitten. I would suspect they have little earned authority or respect from those higher up in the food chain, so they exerted their authority on the kitten. Unfortunately, they should consider that those higher up on the food chain may decide to exert their authority in a similar fashion...
That's all. I have to go wash my mouth out now...