“these ‘missing records’ probably indicate that NO ONE visits him,...”
IMO, that’s possibility A. Presidential “downtime” traditionally involves informal meetings over golf or other conversation-friendly activities. For Biden to hide away for rest completely devoid of business would really say something.
Possibility B: Biden and his handlers don’t want the public to know who visits him because it wouldn’t look good, and/or would help connect important dots.
Possibility C: Alternating episodes of A and B, depending on the autocrat’s condition de jour.
Having him out of the White House also saves a fortune with the carpet shampooing equipment and supplies in the Oval Office.