Partially true. I didn't vote for Stein (I voted PSL), but the Green party is ideologically closer to leftists than the major parties. It's kind of the same on the other side for the Libertarian party, there are more Republicans and non-voters with Libertarian beliefs than there are people who vote Libertarian. Stein herself does seem like something of an opportunist, but she doesn't rely on the same kind of niche cult of personality that Tulsi has built for herself. Most people just know of Stein through the Green party, which does represent various legitimate beliefs.
The policies that we on the left advocate for have the potential to reach a wider audience than just people who are already ideologically committed. By running on a platform that would materially benefit people, it's easier to make the case that people should support the left, regardless of who they are or how they view themselves politically. You're free to write off people like me, but it's not as if we're the only ones who like having healthcare, for instance.
Tulsi is one of countless odious personalities that carve out one specific sliver of the population and speak to them exclusively, and fixate on tiny bits of information that support a narrative that's completely out of line with the broader truth. "If you're anti-war, you should vote Republican. Pay no attention to the man behind the curtain, calling for ever more exorbitant military spending, saber-rattling with everyone, conducting assassinations and bombing campaigns. And pay no attention to the fact that I myself was on Fox News attacking Obama from the right for not being aggressive enough in the War on Terror, and literally described myself as a hawk regarding it."
She is part of a pipeline that takes people with valid, left-leaning criticisms of the Democratic party and convinces them to accept the Republicans as an alternative, despite them being worse in every respect. She's absolute scum, and she discredits people like me, who actually are anti-war, not just when it means criticizing the Democrats. I will always call out her and her ridiculous little fanclub, who have clearly never read an actual goddamn book in their lives. And the same goes for people like Jimmy Dore and Jackson Hinkle too.