Your analogy does not work, as the situation presented requires you to either go to the left or to the right.
In real life, there are many options and gray areas. One of those options is to refuse support to anyone who works against the populace, regardless of their political affiliation.
The world would be much better off watching the US turn far-right and implode than it would be maintaining the status quo.
I would rather watch the US die as a Nazi state than support the lesser of two evils. Remove them as a global superpower. Move out of the way and allow other states to bring better systems of government forward. Maybe something salvageable can be found in the wreckage.
That’s the part Fetterman fails to realize as well: Right now is not okay. Continuing the status quo is not okay.
Your analogy also equates the death of the nation with the death of the self, which is not even remotely true either.
Everyone knows not to negotiate with terrorists, until election season.
Then force your party to support better candidates?