to clarify, it's an impossibility to give it to them irrevocably as under US law you can reclaim a copyright that's been transferred to another party after a statutorily defined period of time
I just looked it up and you're right. Apparently there's no way to sell or give away the copyrights. Ever. You can "transfer" it, license it, whatever... Then suddenly show up and demand it back 35 years later.
This is probably designed for book authors and delinquent publishers that stop selling author's books, then the authors can take back the copyright and go to another publisher.
