I can agree to an extent. Yes Biden has lost his sharpness of his mind over the years, but Mr Burns is estimated to have an IQ of at least 130, yet Biden's IQ is 115.
https://www.quora.com/How-would-you-rank-various-Simpsons-characters-by-IQ
https://www.sociosite.net/famous-person-iq/joe-biden