I misread the account as moving the cat out of sight instead of physically dragging it with a car.
Yeah, they deserve jail time, but 6 months is plenty.
From the info given in the article, I'd agree on six months, or even some kind of supervised probation for the guy on the right. For smiley, I think the longer term is acceptable given we don't put people in mental institutions anymore. He seems to be a guy that will never learn his lesson. I predict when they let him out early in a couple of years, that he'll immediately do something else stupid, or worse, harmful to people.
As the saying goes, some people just need killin'.