Though even this delayed back out might be what the DNC wanted all along. Primaries in the last two elections showed there are a lot of people who want Bernie or other less-establishment politicians. By waiting so long, they basically get to name whomever they want without pretending they should listen to voters.
“The only thing worse than bad leadership is broken leadership” is a quote from my favorite book, and I can imagine the DNC operating from this perspective. Campaigns and primaries would have broken up the party’s voters, and they might just be banking on whatever call they can make themselves.