Why would they release something like this now and not wait until he is officially nominated? Do they want him replaced by a better campaigner?
Suspect that rational Democrat operatives realize that the dementia issue will be used mercilessly ( as it should) by the Trump campaign. Its hard to believe that there are no behind the scenes efforts to ditch Biden. Not even Democrats really believe that the American people will elect an obviously demented, sickly old man to be their President.