Meh, I didn't say I thought it was a particularly effective strategy. Unsurprisingly, Elizabeth Warren is apparently doing much more to effectively push Biden left than Sanders is. But, Sanders is probably (rightly) concluding that within his style of politics, staying in the campaign will have a larger effect than sitting on the sidelines, even if the effect is marginal.
I think he would be a lot better off by calling Biden, trying to get the concessions/promises he can and then stepping out of the race after endorsing him. Obviously he was in a much better position to do this weeks ago.
I just don't get what Bernie is thinking he is getting out of this, it isn't like Biden is polling any worse. If his numbers were sagging I could get it but if anything Bernie is the one that is polling worse.