That logic applies identically to an existing patent. For the issues you mention, there is no distinction between the patent being filed at the PTO and still valid, or being filled at the PTO and disclaimed. In terms of the enforcibility, and patentability of a ““new”” inventions with prior art, there is no legal distinction whatsoever between the prior art being a disclaimed and valid patent, so I don’t think that’s a valid reason to not disclaim it.