@edgarblythe,
I agree with you that Sanders would make a better president, but she’s playing a good game, seen from afar, and I don’t think she's fake. She might be more willing than Sanders to compromise with the powers that be but that can be seen as realistic.
My sense is Sanders fundamentally thinks Warren would be infinitely better than Trump, and that if she wins the presidency it will be a win for progressives. He never said ‘Bernie or burst’, and he must know that she can get the DNC machinery behind her in a big way the moment Biden falters a bit too much. He can’t throw her under the bus. This divide between the left has to work productively towards some synthesis, some temporary resolution and agreement in order to beat Trump, a sine qua non condition to do anything useful towards mitigating climate change, or redistributing wealth and opportunities.