Biden Hiding-Anyone feel the "call in" supporting Kamala was odd?

Biden posts a letter on X announcing his withdrawal from the ticket seems strange for such a monumental announcement (not to mention the signature doesn't match). Then he calls in announcing his support for Kamela (in the age of Zoom, etc). What I found strange about the call was Biden sounded stronger and (dare I say) more coherent than he has in years. Is it beyond the realm of possibility that this call was AI generated? It appears to be one way too. Interesting YT video here about this.