1. What if they're playing the long game, and the goal is not short-term political results, but to influence candidates in the longer term? A losing candidate doesn't necessarily result in a "0 result" in the long term. For example, Barry Goldwater's losing effort in 1964 helped push the Republicans to the right, and Bernie Sanders's losing efforts in 2016 and 2020 helped push the Democrats to the left.
Put a probability to it. What are the odds that the Green Party leading to the reinstatement of an authoritarian president facing prosecution for trying to overthrow the government will make for a healthier democracy in the long-run.
First off, objective scientific research suggests that your claim that the Green Party put Trump into office is false. In Pennsylvania, Clinton would have needed 95% of Jill Stein voters to still go to the polls and vote for her, with zero Jill Stein voters turning to Trump. If it broke even 97% Clinton and 3% Trump, she would still lose. Analyses of voting patterns suggest that in reality most Jill Stein voters would have abstained from voting if Jill Stein was not on the ticket.
Now to answer your misleading question anyway, obviously the odds are dramatically unknowable, and you can't Monday Morning Quarterback a single anecdote and then use that to evaluate all future possibilities.
Like I already pointed out, Barry Goldwater winning the Republican nomination in 1964 likely did far more for the right-wing cause in the long term than nominating Nelson Rockefeller would have. Amazingly, this is true despite the fact that Goldwater lost to LBJ, who then proceeded to sign the Voting Rights Act, a second Civil Rights Act, create Medicare, Medicaid, and food stamps, and nominate Thurgood Marshall to the Supreme Court. Proving that short-term losses do little to predict long-term impact, even when those losses are dramatic.
Also, you are looking at 'influencing candidates' while I think a better process is framing things as 'how candidates are viewed'. Does it matter if the Dems shift further to the left if the perception stays the same or gets worse? Manchin/Synema managed to change perceptions of millions of progressives by watering down many policies that lead to the 'Dems just care about multinationals and wallstreet' narrative in spite of what was actually attempted for example.
Great excuse. Now, what's the excuse for when Obama had the presidency, a solid progressive mandate, and 59 or 60 Dems in the Senate, yet still gifted corporations and banks with damn near the most pro-corporate response imaginable to the economic crisis? Do you not realize that half the young voters you lost were lost right there, they weren't lost from any Synema bullshyt.
Paul Volcker, Alan Greenspan, Robert Rubin, Lawrence Summers, Timothy Geithner....who nominated these people to control our economy? Was that Manchin's fault too?
How about when a dozen Democratic senators (including Feinstein!) voted for Bush's massive 2001 tax cuts and then nearly as many (including Feinstein, Carper, and Wyden) signed on to his Medicare corporate giveaway?
How about when Clinton and numerous democratic legislators decided to join the Republicans and double down on deregulation during the 1990s?
We could go on and on.
2. What if they view Biden as someone who is not "60% okay", but someone whose policies will lead to continued collapse of the environment or society? For instance, if you believed there was a 100% chance that Trump's policies would lead to environmental collapse, and a 99% chance that Biden's policies would lead to environmental collapse, but only a 50% chance that West's policies would do so, wouldn't the game theory options look different?
If you believe these risk levels, feel free to update with your personal weightings and let's have a discussion. If it's just hypothetical, then it's not a variable that can be accurately accounted for yet
I believe that if we continued Trump policies indefinitely, we would face 100% risk of environmental collapse.
I believe that if we continued Biden policies indefinitely, we would face 100% risk of environmental collapse.
Those facts are widely agreed upon by scientists, who have repeatedly said that we need to take MUCH stronger measures if we are going to stave off catastrophic damage to the planet. The only question is when are we going to start? And centrist democrats appear too short-sighted to think we need to start now, they'd prefer to just take baby steps so they don't piss off their corporate contingency, and hope the actual necessary measures are taken by someone else, later.