Biden should be primaried from the left. If the end result is either the primary challenger winning or Biden adopting some more left-leaning positions to win the primary, this will boost Democrats’ chances of winning.
In short - idiocy. First - even Kenndy couldn't beat Carter this way, though he was .... well, Kennedy, and Carter was more conservative, then Biden. And second - Maryland's (and some other states) examples in 2014-2018 clearly show, that there is considerable number of Democrats, who will flatly refuse to vote for your "from the left" candidate.... And this is true even in most Democratic states, while Biden's national electoral victory was rather close. I know no better way to handle Presidency to far-right Republican.. In one phrase - US is NOT a "progressive country", where you could make such experiment with "impunity"...
