alt Hacker News> Surely the person doing so would be responsible for doing so, but are they doing anything wrong?
You're perfectly at liberty to relicense public domain code if you wish.
The only thing you can't do is enforce the new license against people who obtain the code independently - either from the same source you did, or from a different source that doesn't carry your license.
This is correct, and it's not limited to code. I can take the story of Cinderella, create something new out of it, copyright my new work, but Cinderella remains public domain for someone else to do something with.
If I use public domain code in a project under a license, the whole work remains under the license, but not the public domain code.
I'm not sure what the hullabaloo is about.