> But if the government can essentially revoke a private individual or company's copyright merely by incorporating otherwise protected text into legislation, that can have adverse effects on copyright holders.
I don't see a problem with that. Copyright is a privilege granted by the government. If the government wants to revoke that privilege that is their prerogative.
The US constitution states otherwise. It says that Congress is allowed (not required) to grant limited time copyrights to promote the useful arts and sciences. That seems to make it quite explicit that copyright is granted by the government and not just recognized by it.
I don't see a problem with that. Copyright is a privilege granted by the government. If the government wants to revoke that privilege that is their prerogative.