I dont know what the game was
Perhaps they really can't sell a truck without cats, and they didn't want to put the money into it to turn it, or perhaps you were right on their motives
They definitely can't sell it without cats, and they're back ordered pretty bad too, so they'll have to sit on the truck for a long while until they can move it, so I'm not surprised. At least they did make a deal though, and in the end the difference on the trade was way less than the cost if you'd had to install cats yourself.