I read all this sudden consolidation as the silent Obama's quiet hand. We talk about the Democratic establishment, the Democratic establishment is pretty much Obama and his devotees at this point, moreso than the Clintons anyway.
If this was Obamas doing, why hasn't he just openly come out to endorse Biden yet? I know he wants to be seen as not interfering in the election, but it is his own damn vicepresident, he could absolutely get a pass for endorsing him (albeit not from the BernieBros, but they'll hate him regardless).