Is there no bottom to Sanders's egomania? Is he utterly deaf to his own delusional arrogance? He loses... badly... and then walks into the Democratic House caucus and lectures them about how elections don't matter? Don't matter when the alternative is Donald Trump? Don't matter in order to give Hillary a Congress she can work with?
Yes, they booed him, as they should have. They were being polite. The only other response would have been to laugh in his face.
Update: Well, finally. Let's hope he does it with useful energy.
Update 2: Okay, he did the right thing. Much is forgiven.