So if in 2016 the Trump campaign had done the same thing, you'd be fine with the response, "The Trump campaign is not the government."?

I would, yes. In fact, the Trump White House did just that, it’s right there in the thread. Without knowing what the tweets they had removed were, I don’t see evidence of wrongdoing. There are legitimate reasons to have tweets taken down: malicious impersonation, revenge porn (which apparently some of these were), death threats, etc.

But Biden was likely to be elected, members of his staff appointed to government positions and staff at Twitter likely understood that.

Were they? It wasn't clear even for most of a week after the election that Biden was likely to be elected.

it was clear for the whole campaign the odds were pretty even

Is that a defence or further proof of malfeasance?

The Biden campaign, which became the government, perhaps in part due to the assistance provided, requested and received assistance. If the campaign wasn't the government and didn't have the power to compel assistance, why did Twitter help?

Because at least some of the content reported by them was unequivocally bad? Like someone's nudes that were published without consent. Or are you saying that if NYPost decides to run some candidate's children's nudes all of a sudden it's journalism instead of revenge porn?