AFAIC, the final word:
There's no "there" there: Breathless reports (with video!) of Joe Biden "having lost it" are untrue Politics & Elections
In brief: While in France recently for the 80th Anniversary of D-Day remembrance ceremonies, Biden did not try to sit in an imaginary chair. The chair was there – careful use of camera placement was used to imply otherwise. Also while in France, Biden did not hesitate to sit down because he soiled himself. He hesitated to sit down because he was waiting for the speaker following him to make it to the podium and start speaking. While at the G7 Summit in Italy, Biden did not wander off …