"As George W. Bush's victory clarified, the local Nader chapter staged a small march down the middle of the grand floor, to accolades which must have been mainly Republican. They might not have intended the Republicans to win, but they couldn't deny they had affected the way things turned out."

Sorry, I don't see it. A vote for Nader in an essentially two-party election was not a vote for Bush; functionally it was the same as a vote for nobody. And it was a miniscule portion of the votes for nobody in Florida.

The voter turnout in Florida for president was 56% of estimated eligible voters, who numbered over 12 million. Presidential Turnout Percentages of Eligible Voters in 2000

The Nader vote was around 17 thousand. Of the roughly 5.28 million voters who sat it out, many more than 17 thousand at least preferred Gore to Bush, to say nothing of the smaller number necessary to elect him. Compared to the potential Gore voters who did not bother to vote, the Nader vote was conspicuous but utterly trivial--and those voters didn't even WANT Gore.*

If we want to construct counterfactual scenarios, a more plausible one, and one which more reasonably assigns responsibility would be, "Suppose the Gore campaign had been 5% more effective in turning out the vote, then Gore would have won walking away."

(*I have never seen the logic of "You prefer your candidate, therefore you should vote for mine.")