My comment was in the context of a Capabilities Based secure OS. Once you have read-access to a document, you can copy it, and do almost anything else you want

My comment was in the context of a Capabilities Based secure OS. Once you have read-access to a document, you can copy it, and do almost anything else you want with it, it's your choice, and the OS will enforce that choice. DRM and "View but don't allow print" are both completely incompatible with Capabilities based OSs (but you could run a Windows VM on it, and that could have "DRM" in its internal state)