My friends and colleagues @mlinksva and @cwebber and others at Creative Commons worked on an RDF vocabulary for Creative Commons licenses.
https://creativecommons.org/ns
We should probably work on having better support for that vocabulary in ActivityPub servers, and figure out what finer-grained permissions there are.
Contrary to using Twitter or Facebook, you didn't agree to an End User License Agreement for the social web. Your rights here should be pretty broad.