While the far left and right do intersect (see AFD/Linke in Germany and FN/PCF in France), I have trouble considering Bernie as a threat. He does want more government support for the poor, which can seem odd in the USA context. But, that would be useful.
Republicans just peddle hate and racism.
That said, I would not vote for Bernie. I think he would be intolerant of dissent.
If you are talking about intolerance of opposing viewpoints and inability to debate with your concerns, I can agree with that on far left/right.