Just so we're on the same page, each state decides how it chooses candidates to put on the ballot. That's the whole thing going on with DT and the SC right now.
Derived from that power is the president primary, where parties from each state decide who to present as their candidate.
The Democratic National Committee says "Ok, everyone should just submit Biden as the candidate and skip the primary" because that's what they decided is best.
It's now up to the state parties to implement that decision or not. New Hampshire, for example, decided to hold a primary anyway:
But it's politics, so who knows if it'll actually happen. I just want to point out that the national committee doesn't have power over what the states get to do, it's all just a power brokering game.
That's just not how it works. If New Hampshire decides to put Steamboat Willy on the ballot, only the SC could stop them, maybe. it's kind of up in the air right now apparently.
Realistically, no one wants to give up that sweet national committee money, so they'll probably cave, and it is the rich owning democracy. That's why I kept saying you'd have to light money on fire to get it done, but it could theoretically be done: you just have to grease a lot of wheels.