To answer your question, there is absolutely nothing wrong with Jill Stein. Just as there is nothing wrong with Nader. Nader spoke at my college once actually, and I adore him. But a Nader vote in 2000 was an irresponsible and wasteful vote (even in blue states) and Bernie has already said that if he doesn’t get the nomination, he won’t run as an independent so as to not cause a repeat of Election 2000. Bernie has also said he will support Clinton in that outcome, because he knows there’s not a chance in hell that the green party nominee would beat the democratic nominee in this election.