That's true. But even if it's not optimal, I think it's a good play, regardless of alignment. Saying "I will hunt you down and expose your role to everyone," is aggressive, but that's kinda what you need to get results.
It's only scummy if we have excellent reasons to believe that the planner is town-aligned. Otherwise discussion is a good thing. Mafia have more information and more heads to put together than we do. If we can figure something out, they probably can too.
Also, as Rag mentioned, buying an item is equally helpful for both town and scum, because one team buying something denies the other team the opportunity. I'm inclined to think KoD is town, but more because they plan to publicly reveal the role than because they bought the item.