If they live in swing states they are.
Ideally third party candidates could get concessions from either Republicans or democrats in exchange for an endorsement. Kennedy got some completely insane concessions from trump for example.
But Stein hasn't been reported to have asked the dems for anything. Which means the green party is trying to get trump elected. My guess is that Stein got concessions from trump to stay in the race.
He probably got to avoid having sex tapes released. Epstein was probably working with multiple intelligence agencies. The Russians probably just paid the most for those videos.