If you actually care, then simply configure your client to leech. Every client I've ever used or heard of supports this.
But more to the point, getting tricked into seeding a copyrighted movie by a torrent masquerading as a Debian ISO isn't something that actually happens. That's absurd FUD.
> "This is just fear mongering, the same exact thing can happen with a web browser, I click a link to view an image of a cat but... oops, it was actually a Getty copyrighted picture of a dog! Oh nooooo."
No-one cares whether you download an open-sourced photo of a cat or a copyrighted photo of a dog.
But more to the point, getting tricked into seeding a copyrighted movie by a torrent masquerading as a Debian ISO isn't something that actually happens. That's absurd FUD.