No, they win with 51% of the vote. After they've stolen the extra votes based second choice votes.
Only if every single Green voter chose the Dem as their second place vote (which is by no means a given). And if they did, then that would mean more people preferred the Democrat to the Republican, so the Democrat would win. That's how elections are supposed to work. Would you prefer a scheme where a candidate can win, even if most of the voters don't like them? That's how it works now, but how is that better?
The cool thing, from the third-party voter perspective, is that there is a solid record of how many people preferred the Greens over Democrats, and that WILL have an influence.
I've worked with activist libertarians (big and little "L") for most of my life. And there is a consistent phenomenon where polling suggest that 15-20% of voters support libertarian policies. Yet the election rolls around and we get 1% of the vote. That clearly doesn't reflect reality. With RCV, there's no excuse for libertarian voters to not vote for a libertarian candidate as their first choice, and we would, finally, get an accurate read on how many voters preferred libertarians over Republicans.
Sorry to say, but I think you're just responding to RCV from the perspective of a duopoly partisan looking to protect the status quo. You guys love lesser-of-two-evils because it means you don't need to front a good candidate. All you need to do is demonize the 'other' one. So, you're right in one respect, RCV is a direct threat to the
that shitshow. But that's the point.