Well, you can ask plugin owners to upload a particular file with a particular key to their plugin on WordPress.org. That way they can prove they have access, and they should be allowed ownership of the plugin on the fork.
No, that's not the "stealing" I'm referring to. Instead of guessing what I could mean, just read my response to the person who first asked what I mean with "stealing".
Well, you can ask plugin owners to upload a particular file with a particular key to their plugin on WordPress.org. That way they can prove they have access, and they should be allowed ownership of the plugin on the fork.