Subject: Re: Why would AOC & Bernie Support Biden?
Because they have safe seats.

The bleeding edge of elected officials calling for Biden to step aside, or getting cagey on their public statements of support, are those in frontline districts facing competitive elections. If they take a public stand supporting Biden - or even just stay silent - then they're going to pay a heavy price if he goes out at some later event and acts like he's incapable of serving. If Biden isn't able to serve, they have to distance themselves or they'll lose their seats.

Pols like AOC and Bernie don't face such concerns.

Which is a big reason why it appears there's an ideological and demographic split in public support for Biden. Hardcore progressives and minority electeds (especially black electeds) often come from safe seats, and most have already gotten through their primaries.