It is. And you didn't. You're simplifying an election down into a narrative (2016 is Bernies fault!!!!) that cannot be proven true, has plenty of evidence contrary, and then you're trying to shame people into seeing things your way.
What you've said is that a vote for a third party candidate will help the least desirable candidate become elected over the less desirable (but more probable) candidate.
That's logically unsound and wrong.
Essentially, you're saying "You’re wasting your vote" which completely ignores and denigrates the principles and convictions that other people prioritize more highly than you do when voting. I'd ask you to just pay attention to yourself...don't try to bully your opinion onto others for voting their conscience.
Honestly, if you can become less supportive of a candidate and his/her platform just based on their followers, you're doing it wrong and you might want to take a step back and ask yourself how you let your decisions become influenced that way.