To clarify, that case was thrown out becuase plaintiffs lacked standing. I guess that counts as the DNC winning?

In Wilding v DNC:

Plaintiffs filed a putative class action alleging that during the 2016 Democratic presidential primaries the DNC and its chairwoman improperly tipped the scales in favor of former Secretary of State Hillary Clinton, who was challenging Senator Bernie Sanders for the Democratic presidential nomination.

This website reports a similar quote about replacing candidates though with more context:

[I]f you had a charity where somebody said, Hey, I'm gonna take this money and use it for a specific purpose, X, and they pocketed it and stole the money, of course that's different. But here, where you have a party that's saying, We're gonna, you know, choose our standard bearer, and we're gonna follow these general rules of the road, which we are voluntarily deciding, we could have — and we could have voluntarily decided that, Look, we're gonna go into back rooms like they used to and smoke cigars and pick the candidate that way. That's not the way it was done. But they could have. And that would have also been their right, and it would drag the Court well into party politics, internal party politics to answer those questions." - DNC attorney Bruce Spiva

That isn't the entire quote and it seems to be missing some important context. The link to the transcript is dead unfortunately.

Even if that is the complete context:

• I don't know if what Spiva is saying is legally true. As the Trump trial has shown us just because a lawyer argues something in court does not mean it's true or legal.
• Assuming what Spiva is saying was true then and is still true now, he also says "And that would have also been their right, and it would drag the Court well into party politics, internal party politics to answer those questions." I'm not 100% sure what this means because of the missing context, but it seems to imply simply picking the candidate in a cigar filled room would have brought legal trouble to the DNC.

It's still not clear the DNC can unilaterally replace Biden as the candidate without his consent. If they did it would open a whole host of new problems, the least of which is how do the pick the new nominee now that nearly all states have already held their primaries.

Saying "it's a simple thing that has to happen, just do it DNC" is just blatant misinformation.

Also, Spiva appears to no longer work for the DNC. It isn't clear if their current counsel holds the same opinion.